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WATER FOR EVERYBODY
A Selection of Appropriate Technologies to be used for Drinkable Water
EMAS
Popular autodidactic Training
Supporting text to EMAS films, for all those who wish to improve drinkable water, micro irrigation or basic sanitation.
Wolfgang Buchner
5th
edition, 2006 Transl. Dublin Tec. Institute
Escuela Móvil Aguas y Saneamiento Básico EMAS * Wolfgang Eloy Buchner Urbanización Amor de Dios, La Florida Calle 1 Nº 8 La Paz - Bolivia Tel/Fax.: (00591 -2) 2740286 e-mail : [email protected]
* : (EMAS Water and Basic Sanitation Mobile School)
2
CONTENTS 1. Introduction for the user of these texts............................................................................................ 5
2. A note on Patent of the "Alternative System for Drinkable Water" : ................................................. 6
3. EMAS pump ..................................................................................................................................... 7
Maintaining the pump ......................................................................................................................... 8
Pedal adapted EMAS pumps .............................................................................................................. 10
1) Pumping from a Lake of River. ................................................................................................... 10
2) Pumping from twin wells ........................................................................................................... 11
3) Pumping from an excavated well. .............................................................................................. 11
Remote manual pumping with the EMAS pump ................................................................................. 12
Air chamber ................................................................................................................................... 12
Connections ................................................................................................................................... 12
Impounding from small springs ...................................................................................................... 14
Plastering the walls with cement, and covering them with a stone arch. ........................................ 14
Impounding a spring (How to). ....................................................................................................... 15
Using a Filtration gallery to impound a Spring ................................................................................ 17
Intake of surface waters from a lagoon, breakwater, river ............................................................. 19
Single wells with underground reservoirs or refilled EMAS drilled wells withcompensation reservoirs
.......................................................................................................................................................... 21
The EMAS storage/reservoir Well. ................................................................................................. 21
4. Traditional well with defective metallic pump replaced by an EMAS pump, and remote manual
pumping ................................................................................................................................................ 22
5. Setting up an EMAS pump in a well which has no antecedent of a former pump ............................ 23
Setting up an EMAS pump in a wide well drilled, or in an excavated large well .................................. 24
Excavated well ............................................................................................................................... 24
The hydraulic ram .............................................................................................................................. 25
What is the Hydraulic ram? ............................................................................................................ 25
Household installation ....................................................................................................................... 29
How to eliminate iron ........................................................................................................................ 30
Bottle filter and EMAS filtration plant ................................................................................................ 31
EMAS manual deep drilling (washing) ............................................................................................ 33
3
The EMAS drilling system using suction ............................................................................................. 37
EMAS multiwell ................................................................................................................................. 39
EMAS design for rainwater Harvesting ............................................................................................... 40
The roof ......................................................................................................................................... 40
Water volume ................................................................................................................................ 40
Collection ...................................................................................................................................... 41
The filter ........................................................................................................................................ 41
EMAS Cisterns................................................................................................................................ 42
Distribution to the cisterns (underground tanks) ............................................................................ 42
Exceptions for the interpretation of bacteriological analysis in pluvial impounding ........................ 42
EMAS Cisterns ................................................................................................................................... 43
Multiple uses of a cistern ............................................................................................................... 43
Building an EMAS cistern of vertical Design. ................................................................................... 43
The curbstone ................................................................................................................................ 43
Mud cakes ..................................................................................................................................... 44
Pure cement whitewash ................................................................................................................ 44
The cover ....................................................................................................................................... 45
Setting up the pump; how to clean it ............................................................................................. 45
Building a Horizontal cistern .......................................................................................................... 45
Surface cistern ................................................................................................................................... 48
Semi embedded cistern ..................................................................................................................... 49
Failed excavated well transformed into a cistern ............................................................................... 50
Advice to make it waterproof ......................................................................................................... 50
Disinfecting with chlorine .............................................................................................................. 50
Supplementary Cistern ...................................................................................................................... 52
Combined impoundment, a drilled well containing salty water, and harvested rainwater .................. 54
Possibilities of using motorized pumps for EMAS wells ...................................................................... 55
Single suction................................................................................................................................. 55
Use of a motorized pump in an EMAS well with a deeper static level (pump brought down in a dry
well). ................................................................................................................................................. 56
A Motorized pump in a well excavated and deepened with the EMAS system ................................ 57
Pumping with compressed air ............................................................................................................ 58
4
The EMAS latrine does not affect aquifers, it is comfortable, hygienic and almost odorless. .............. 60
How to build a laundry tile ................................................................................................................. 63
How to build a seat for a latrine ......................................................................................................... 64
EMAS micro irrigation system ............................................................................................................ 65
Pedal adapted EMAS pumps for irrigation.......................................................................................... 66
Small ferro-cement tank or 'pitcher' .................................................................................................. 69
Building PVC accessories .................................................................................................................... 71
Windmill with the EMAS pump .......................................................................................................... 75
EMAS design solar heater with no tank .............................................................................................. 76
5
INTRODUCTION FOR THE USER OF THESE TEXTS The ESCUELA MOVIL AGUAS Y SANEAMIENTO BASICO (EMAS) was created to promote the technology of
potable water supply, and water for micro irrigation, in rural and suburban areas. Its founder and
academic director is Mr. Wolfgang Eloy Buchner. EMAS receives financial support from a group of
volunteers based in Munich, Germany. EMAS does not give direct financial support to projects, but is
disposed to help local initiatives by providing practical and theoretical training through the "learning -
performing" method. EMAS is disposed to work in an advisory role, and has served as
advisors/consultants, to various projects in Latin America, Africa and Asia.
The EMAS concept is based on a variety of simple technologies such as manual drilling of deep wells,
manual pumps built by the users themselves, small wells from springs, ferro-cement tanks, sanitary
installations and much more. The student/user learns these simple technologies, and is therefore in a
position after a period of practical instruction to maintain and replicate these technologies in his/her
locale. An important concept in this methodology is the training of drillers, who are themselves suppliers
of potable water, at a local level. These professionals working in rural areas, have for many years offered
their skills and experience to water users, while at the same time transmitting their skills to others.
The purpose of this book is to facilitate the decision making process, for both professional and lay
persons working in the area of water supply and sanitation, in arriving at a low tech sustainable solution
to water/wastewater problems. The text is based on experiences, gathered on site, during many years of
labour and investigation. EMAS authorizes copying of the text, but requests that those who do utilise
the text inform EMAS of it use and purpose.
I also wish to express my deep gratitude to my wife and children for their understanding of my absence
from our home during those long periods when I was away at training schools, prospecting sites and
testing sites.
Wolfgang Eligius Buchner, Author.
6
A NOTE ON PATENT OF THE "ALTERNATIVE SYSTEM FOR POTABLE WATER" : The drilling system and FLEXI pumps have been patented in Bolivia and registered as Number 5221,
dated March 18, 1996 in the name of Wolfgang E. Buchner.
As owner of this patent I grant my express authorization for the use of this technology to help the
needy, with no charge, to any driller, local artisan or layperson regardless of where they have learned
their skills.
The price of components (wells, pumps, filters, etc.) will vary according to costs in each country. Usually
they consist of : 1/3 = cost of materials; 1/3 = cost of transport, labour, etc.; and 1/3 = cost to cover
failures, or replacements.
7
EMAS PUMP
EMAS FLEXI pumps are also known as OPS - FLEXI pumps, as, a number of years ago EMAS granted a
free license of its patent to the Pan-American and World Health Organization. They are manual
pumps that the user can easily learn to build, as they are made of PVC or of Polyethylene piping. By
varying the pipe size (using pipes of a larger
or smaller diameter) the pressure of the
water or the water volume pumped can be
regulated. All EMAS pumps have an outlet
pressure that allows pumping up to 60
metres height, or 2 Km horizontally. The
flow varies between 0.2 and 1 litre per
pulse depending on the pump model.
In Bolivia, the cost of a 12 metre length
standard pump is approximately 20 Euros.
EMAS pumps are multipurpose. They can be installed in wells drilled with a reduced diameter (EMAS
system), machine drilled wells, hand excavated wells, cisterns, micro systems and pumping
station/plants. Their main advantage is that the user can build and replicate them him/herself,
cheaply, and with locally available materials from the hardware store. Once a well is cleaned and
activated, the pump can be installed.
EMAS has developed this manual pump which
is cheap, simple to construct and maintain and
fits a narrow well of only 1 1/2" diameter
(EMAS well).
The standard pump type comprises two rigid
PVC pipes, or two polyethylene hoses. The
pipe with the largest diameter, 1 inch, forms
the cylinder, and the other one, of 1/2 inch
diameter, operates as both a connecting rod
and an outlet pipe. The pump operates in a
similar manner to a piston pump, the only
difference being that the water is ejected
through the connecting rod itself. The handle
grip or holder consists of a T with two lateral
nipples, one of them blind, and the other one
with an open outlet through which the water
exits. The 1 metre metallic tube goes in and
out of the well, and functions as a friction
component with the cylinder acting as guide. At its lower end, it is connected to the outlet pipe or
the connecting rod. The connecting rod ends at the bottom of the pump, with the piston valve. The
downward motion of the piston decreases the volume of water and it is pushed upwards and is
8
ejected through the outlet nipple. The cylinder pipe is connected, in its upper section to a reduction
sleeve which acts as a metallic guide, usually a 1" galvanized iron nipple, or a 1" - 3/4" reduction
coupling which also supplies friction. The standing, or intake valve is attached at the lower end.
Pumping can reach a pressure up to 5 bars, thus
allowing for direct pumping from an
underground water source to an elevated
reservoir. The pump also allows for the
extraction of water from a well of 40 metres
depth using a 1" cylinder. The flow from each
pulse depends on the height to which the pump
handle is lifted, but as a rule, 0.3 and 0.5 litres
per pulse is normal, resulting in 15 to 30 litres
per minute from a 1" pump. High pressure EMAS
pumps can lift water to a height of 100 metres.
However, the cylinder diameter of high pressure
pumps is reduced. The opposite occurs with
cylinders larger than one inch. Here the flow
increases, but the pressure decreases.
Valves are built using PVC pipes threaded with a
3/4" screw type (standard valve) and PVC pipes
threaded with 1/2" (universal valve) with a small
marble inside. To increase compression and
prevent loss of flow, rubber rings are placed on
the piston valve. The valves or rubber rings can
be easily replaced where there is abrasion or
deterioration The same holds for welding PVC adapters (male and female), to construct valves.
The pump looks like a single pipe with an iron handle. The pump fits exactly into the well, of 1 1/2"
diameter, drilled with the EMAS system . The pump is submerged to about 3m below the depth/level
of the well. The length/depth of the EMAS pump most commonly used is between 6 and 12 metres,
but there are wells that need as much as 40 metre pumps.
In pumping to a distant or elevated site, a rubber hose, from 1 to 2 metres in length, is attached to
the outlet nipple, in order to allow for the upward and downward motion. The other end of the hose
is connected to the outlet line going to the elevated reservoir. To convert from a pulsing stream to a
continuous stream from a well, an air chamber can be added (see module titled "water for all places-
hydraulic ram").
Maintaining the pump
Regular maintenance of a well and an EMAS pump is important to ensure good quality water and an
operating pump. It is also advisable to vary the position of the pump handle as this distributes the
abrasion evenly over the outlet valve, thus increasing the valve life span.
When the valve loses pressure , it is normally as a result of the gasket being worn out. A temporary
solution may be achieved by tapping the base, when it is under pressure or by removing the screw
9
thread. When this has been tried and does not work, the gasket can be replaced by cutting a new
piece from a tyre. The outlet valve has a life span of about 500,000 litres. After this amount of use it
should be replaced. In Bolivia its price is equivalent to US$ 1.50. This work can be carried out by the
local driller/user.
The EMAS pump will require 3 - 4 valve changes, maximum. Experience shows that the plastic pipes
rarely last longer than this and wear out. Pumps made of PVC pipes tend to wear out the couplings
first, and as a result the bell becomes pierced. This can be solved by cutting the defective bell and
replacing the coupling. To avoid water
between the guide pipe and the handle
when pumping under pressure, drill a 1
cm hole approximately 1.5 metres below
the handle in the cylinder pipe. This will
return the water to the well.
Care should be taken when pumping to
avoid striking the metallic guide with the T
(Handle). This can damage the plastic tube
or it may part/slide from the layer that
fastens the cylinder (1" pipe) and the
whole cylinder may fall into the well.
Where the pump cylinder has fallen, ask for help from the driller. With a screw thread at the sharp
end it may be possible to fish out/recover the pump. Do not use sticks or other objects.
It is also good practice to cover the rubber between the well and
the pump to so as to protect it from sunlight. Failure to take this
precaution can lead to the cylinder unfastening. A piece of cloth
tied with thread or wire will suffice.
In some instances where the intake valve is defective the pump
may continue pumping if operated by the user by pumping in
such a manner as to accelerate the pipe upwards and stopping
suddenly ( a reverse hydraulic ram). Where the outlet valve fails
emergency pumping can also take place by removing the outlet
pipe and using the cylinder as a reverse hydraulic ram.
The introduction and removal of long pumps from/to deep wells,
always runs the risk of pipes breaking . In order to avoid such
damage, arch and bend the pump as shown in the photograph.
Some people may wish to protect their pump from unauthorised use. This can be done by welding a
ring to the guide pipe, and another ring to the T holder and fitting a padlock (see photograph) .
10
PEDAL ADAPTED EMAS PUMPS There are different types of pedal operated pumps,
which can be used in irrigation, in the rearing of
livestock or for domestic use. Pedal power is more
efficient than manual power, as the muscular
structure of the legs is stronger than that of the
arms.
Pedal pumping is similar to a children's seesaw. In
contrast to other models, EMAS pumps have the
advantage of being able to pump water over long
distances, or to raise it to a height of up to 40
metres. Pumps can be purpose built for flow or
height, by using different diameter cylinders. The
EMAS pedal system has two twin pumps operated
by a lever with equal arms. When one side goes up,
the other side goes down. On the upstroke one
cylinder is filled with water and at the same time the
other cylinder is emptied, because its piston goes
down. There are three different construction types.
1) Pumping from a Lake or River.
This application uses a compact and portable
mechanism. The valves and accessories are made of
galvanized pipes similar to the ones used in the mud
pump for drilling wells. Both valves are located at the
same level, at the lower part of the pump, and they
form the valve head. The upper part has a 1 inch
screw thread, to which the reduction coupling for the
plastic cylinder pipe is threaded. The advantage of a
PVC cylinder is that it is polished, and therefore it has
much less friction than a steel pipe. The diameter of
the cylinder varies according to the pressure
required. Usually diameters of 1.5 to 2 inches are
used for irrigation. The cylinder is a pipe of about 40
cm length, with a screw thread on both sides. A
reduction coupling connects it with the head. On its
upper part it has another reduction coupling which
operates as a guide for the connecting rod. The piston
is simply a piece of galvanized pipe, plugged on its
lower side. If the piston is an exact fit it needs no
gasket, otherwise the gasket can be made of tire or
cloth. The connecting rod has two hinges for movement fastened on the pedal board. All the
framework is welded and made of 1/2 inch iron.
11
2) Pumping from twin wells
The twin wells system can be used where the subsoil
has good quality aquifers and in cases where the land is
suitable for drilling. Using the EMAS system, two wells
are drilled at a distance of 80 cm apart. Install two
EMAS pumps. If a diameter of 2 “ is used then a flow
pump can be installed, but if the water is below 10
metres or if the recharge is not up to standard, it is
advisable to use 1 “ standard pumps. The rest of the
mechanism is relatively easy to install. It involves
installing the see saw and arranging the connecting rod
with two hinges on both ends. The connecting rod is
joined to the handle by welding a 3/4" pipe which has
been cut lengthwise and operates as a gearing, to
which the holder is tied with a pneumatic tyre strip (see
the illustration).
3) Pumping from an excavated well.
This system is similar to the system used in pumping from a twin well, however in this instance the
wells are set up by side, 80 cm apart. The shaft of the see saw must have the same inclination/angle
as the pumps. As a result the balancing board will have an inclination making it more difficult to
operate. This can be easily solved by using two Platforms, which will operate as wedges on the board
and serve to level it.
12
REMOTE MANUAL PUMPING WITH THE EMAS PUMP The EMAS concept is not confined to pumps and low-cost drilling techniques, but also proposes
complete solutions, from the water source to the faucet/tap in the home. The standard type EMAS
pump pumps water at a pressure up to 5 bar, resulting in pumped water that can reach a height of
50 metres. When pumped horizontally at this pressure, water can be pumped up to 2km, using the
correct diameter pipe. For instance a 1/2" pipe will allow water to be pumped 500 m.
Air chamber
A characteristic of the EMAS pump is its pulsed flow. This is very difficult to conduct through a water
pipe as the pulsed flow behaves as a battering ram and gives rise to increased friction. The pulsed
flow most be converted to continuous stream. This can be done by means of an air chamber. The air
chamber is dealt with in the section of this manual on Hydraulic Rams. The low cost/tech EMAS
solution is a PET plastic bottle.
Connections
There are several ways to connect the
EMAS pump to a village/number of houses.
Perhaps the easiest to operate is the
system that takes the "star" shape,
whereby each house lays out its water
pipes from the well along a straight line.
Although this system requires more piping
and a higher cost, it has the advantage that
13
it is easy to operate. All that is required of the user is to go to the well, shut off the other distribution
faucets/taps and then pump. There is no need to walk around to individually shut the other
connections.
Where the star/straight set up is inappropriate, then the main faucet/tap may be shared, as
indicated in the illustration.
To fill the ferro-cement
reservoir at a particular
dwelling/house all stopcocks
of other branches must first
be shut before pumping. To
facilitate easy operation of
this system over long
distances, it is useful to turn
off the stopcock, located
before each individual tank,
when the tank is full. This will
increase the pressure on the
water pipe, the pump itself will stiffen and the pump operator will notice the change and can
proceed to the next tank. This avoids the need to communicate over long distances.
14
IMPOUNDING FROM SMALL SPRINGS Some water supplies use open sources which show very weak water filtration. These sources,
without impoundment, are not suited to exploitation by a piped water system serving many
dwellings/houses. Though the existing water source supplies many dwellings/house, it is
unprotected and open to pollution, with even pigs and other animals bathing in the source when it is
left unattended. In these situations the most suitable solution is to impound the source and install a
manual pump.
To impound these small springs/sources, EMAS has developed the following method :
A stone gallery serves as a filter which discharges into a 200 litre ferro-cement "pitcher"/jug which
serves as a storage. This is easy to construct and costs the same as 2 bags of cement, approximately.
Where one gallery/pitcher structure does not supply the required capacity, more than one
gallery/pitcher structure may be used. If the storage design volume is greater than 1000 litres it is
advisable to dig carefully around the spring until a large enough deposit/reservoir is obtained. If the
soil is not firm, it is worthwhile to do this
Plastering the walls with cement, and covering them with a stone arch.
The following points should be considered before undertaking any design or construction work:
1 . Has the volume of water from the spring varied much over its period of use? Has it ever
run dry?
2 . What volume of water does the spring produce per day / hour / minute / second ?
3 . How many people use the spring and abstract water from it? What is the present
demand?
4 . What is maximum daily demand? What is the water consumption during peak hours?
5 . What other water sources still exist in the area and are used?
6 . Could water supply be increased with an additional impounding of a spring/water
source?
15
These considerations are also applicable to excavated wells, as it is of no importance as to whether
the filtration is located at one, two or 10 metres depth. Please see reservoir well, below.
Impounding a spring (How to)
Firstly all loose material (sticks, mud, stones, garbage, etc.) must be removed from the filtration
area.
Next the rate of filtration (volume) should be measured by counting how many buckets can be filled
during a certain predetermined time. This will allow the volume to be determined, in litres per
second, per minute or per hour, where the filtration is poor. It is also necessary to calculate what
storage volume of water to design for. For example, a ferro-cement tank of volume 200 litres may be
used but this volume can be augmented by putting a filtrating gallery around it, which can also store
100 litres.
Where a tank is used the well has to be shaped to allow space for the tank and the filtrating gallery
around it. The ferro-cement tank has lateral bores on the lower section of the tank through which
water enters. A filter of stones should be built, around the tank, in the shape of a tunnel. This area
can then be filled with water and can serve as an additional reservoir. Next attach the guide pipe to
the tank which is one measure larger than the pump cylinder.
On top of the filter place a rip rap layer, then some thick sand and on top of it, a clay layer- about 30
- 60 cm - which will compact. Finally flatten the surface and a place a polyethylene film (nylon,
oilcloth) on it.
The compacted earth and the polyethylene film render the surface waterproof . In order to protect
this layer another layer of fine material must be spread on the film. This protection layer should be
about 20 cm in depth and compacted. Finally stone paving should be put in place. This avoids mud
forming when water is spilled in pumping. A slope also avoids pools of stagnant water forming.
16
It is also advisable to construct a cement layer around the pump to avoid any infiltration issues from
fissures etc and to avoid problems with stones loosening etc. As further precaution a tyre may be
used as an additional platform. The final task is to introduce the FLEXI pump to the guide pipe.
Using an arch or a vault to impound is similar to the above process. However the cavern, built of
stones or bricks is used in place of the ferro-cement tank. As previously an arched board is used, on
which the stones are arranged. By using this mould the arch can be constructed line by line along the
board. The last segment must be put in place without the board as otherwise it would remain inside.
When the stones of each segment have been put in place, a cement mortar is spread in the space
between the stones or bricks, to fix the arch or vault.
The arch is an advantage when impounding on rock, or if the earth is firm enough, as the use of an
arch in these cases means walls are not required. Note: If stones are not available, well baked
bricks may be used.
17
USING A FILTRATION GALLERY TO IMPOUND A SPRING Underground water flows naturally from a Spring. There are various kinds of Springs :
Springs have different properties;
Some have a fluctuating volume/flow, varying according to the season; others maintain a permanent
volume; other springs decrease during the rainy season, and increase in the dry season; some of
them have a scattered source, while others have only one stream; some are thermal mineral springs
etc.
It is important to characterise and classify a spring before impounding it. This should be done
carefully making sure that any impermeable clay strip that is present is not perforated This also
applies to the porous material at the bottom of the well, where water can also be lost. This is
particularly applicable when the source of the spring is a foothill/s. As a rule too much scraping does
not increase the volume of the spring, and if it does, it is short lived.
When impounding from a spring special care must be taken to protect against the possibility of
pollution. Sometimes due to poor practice, it is not the spring that is impounded but the stream
created by the impounding structure. This stream can accumulate pollutants on its way to the point
of intake.
The classic and correct form of impounding a spring is the construction of a filtrating gallery. A
filtrating gallery is an underground tunnel wherein water is accumulated. Filtrating galleries can be
constructed using different building materials, for instance cement piping (though care should be
exercised with these as aggressive water will dissolve some materials) plastic piping with grooves (if
the grooves are too thin, roots may cover them, and where the pipe diameter is narrow diameter,
roots may cover the pipe); water resistant wood or board, double baked bricks or locally available
stones. The latter is often the cheapest and best option.
Stones have the advantage of offering good resistance and of allowing a larger underground channel
to be constructed. (To impound a volume of 1 litre / second, a 30 x 30 cm channel will suffice). The
channel should be covered with flat stones. The top of the channel should be covered with gravel
and rip rap. Cover the rip rap with at least 60 cm of Fertile soil. It is advisable to mark the
underground location of the channel with big stones or other signposts, (as a reminder) and care
18
should be taken to prevent weeds from growing in it. The filtrating Gallery and the underground
gallery also Prevents entry of and wash out by polluted water.
The use of Filtrating galleries to impound underground sources from underneath a river bed is quite
common. When the river floods, the underground structure remains intact..
In industrialized countries, this method is also used for impounding coastal filtration from rivers and
lakes, in order to obtain a better quality water.
19
INTAKE OF SURFACE WATERS FROM A LAGOON, BREAKWATER, RIVER Where no underground sources of sufficient volume or adequate quality is available, consideration
should be given to using surface water. This is also the case where water sources are too deep to
extract economically. Where a river or stream is not available stagnant water may be utilised.
Water may be abstracted from natural and artificial lagoons, whether permanent or temporary.
Artificial lagoons are also called breakwaters, cofferdams, ditches, etc. Generally they are excavated
with heavy machinery at a lowly situated site. Pluvial water from ditches or ravines accumulate there
and this can serve as a volume stored for the drier months. In many places these breakwaters are
the only water source for the human and animal population. Animals drink from sources, people
wash their clothing in them and they may also drink this water. Strong winds may also carry all kinds
of dust into these sources. Therefore these sources are usually quite polluted, even though they are
home to many different types of aquatic plants and microorganisms which assist in the degradation
of the polluting matter.
It is also important to protect the breakwater from chemical pollutants such as pesticides, oils and
other poisonous substances.
The diagram above shows a method of impounding water from a lagoon. This method can supply
water to several dwellings. It is important that the intake be located as deep as possible, but at least
about 20 cm above the bottom of the lagoon, as an anaerobic mud can form at the bottom, and give
the water an unwelcome flavour and colour. The deeper the intake the fresher the water will be,
and also maximum water volume will be available at all times.
20
The prefilter pipe should have a larger diameter than the intake pipe. It (the pre filter pipe) also has
grooves and is covered with a synthetic cloth lining. The cloth can be a bag sewn from a synthetic
blanket, fastened to the pre filter pipe.
The slow filter is located a few metres from the breakwater. It can be a round or square excavation,
built in a similar manner to the cistern. It has a stop cock at the intake which should only be used
and shut when or if the filter is obstructed. Where the filter is blocked the sand must be drained, and
the crust that forms on the surface of the sand must be removed. This can be done using a ruler or
some such tool. It is almost impossible when cleaning a sand filter not to remove some sand.
Therefore after cleaning the sand filter should be topped up with new sand.
At the bottom of the filter there is a screen with grooved plastic pipes which is covered with
polyester cloth, the same as in wells drilled with the EMAS system. Water passes slowly through the
fine sand where, microbes are retained. The water flows through the cloth to the grooved pipe, and
continues to the cistern. Before it flows into the cistern, it has to pass through another stop cock.
The purpose of this stop cock is to regulate the speed of water flow through the slow filter, and
therefore to determine the quality of the filtered water. The water then collects in the cistern.
Usually potable water is pumped to the ferro-cement tanks serving each dwelling.
Sometimes the water may still be turbid, although it has passed through the slow filter. Where this
occurs flocculation may be promoted by pouring some aluminium sulfate from the control pipe into
the cistern. (A natural source of aluminium sulfate can be locally available saltpetre). The exact
amount required should be determined through tests on small quantities of water removed from
the source. Usually 1 - 2 spoonfuls of aluminium sulfate are sufficient for a 5000 litre cistern. After
the flocculation, the turbid particles are deposited at the bottom of the cistern. By inserting the
EMAS pump through the control pipe of the cistern, the sediments may be removed in a similar
manner to cleaning a swimming pool. Once clear water has been obtained, disinfection with chlorine
is carried out. The chlorine dosage depends on the size of the cistern.
Where surface waters are excessively muddy, for instance from a river or from a new breakwater
which has no aquatic plants, it is advisable to promote flocculation and sedimentation before the
water reaches the slow filter. Sometimes muddy waters from rivers can flocculate by themselves,
especially when they are stagnant, and they may not need aluminium sulfate. In such cases a pool
may be dug beside the river, and water conveyed from this pool to the slow filter. If no flocculation
occurs in a new breakwater, it is wiser to build a cistern or a flocculation tank and to dose the water
with the appropriate amount of aluminium sulfate , before the water reaches the filter.
21
SINGLE WELLS WITH UNDERGROUND RESERVOIRS OR REFILLED EMAS DRILLED WELLS
WITH COMPENSATION RESERVOIRS Refilled wells are bored wells filled with material, generally soil. They are commonly used in Asia and
in other parts of the world. Their advantage is that
construction is cheap, as they do not require an inner
lining, and they also provide protection against
pollution. The disadvantage is that they can rarely be
filled with sand, and when the phreatic level drops
during years of drought, they cannot be deepened.
The EMAS storage/reservoir Well.
The EMAS storage/reservoir well provides an ideal
solution in areas with weak aquifers. Its cost is much
lower than that of an excavated, coated well. It is
waterproof, free from pollution, hygienic and in
periods of low water it maintains its storage. It also has
a higher yield, and its excavation is less dangerous. It
also has the advantage that the depth of the well, the
volume/flow of water and the quality are known
before excavation.
Drilling is carried out as per the normal EMAS method.
If the aquifer is not sufficient to support direct
pumping, a ferro-cement tank can be used as a
reservoir to compensate for this.
To facilitate this excavate around the EMAS well down
to a few metres below the phreatic level. The
geological profile of the well will be known from
drilling, and in this example it is clayey. Therefore
water will be scarce, and there will be difficulties when
digging.
When the excavation is finished, a pre manufactured
ferro-cement tank is lowered down, below the well
pipe, and some holes are made to the lower end of the
pipe, where it sits in the bottom of the tank. Upon
pumping, water will flow through these holes from the
tank to the well, partially feeding the pump. When no
pumping takes place, water in the well rises, filling the
tank once more. Therefore the tank compensates for the higher water demand required when
pumping. The size of the tank depends on the volume of the well drilled, and on the demand. The
usual size is 150 litres (To set up the ferro-cement tank, please consult the "ferro-cement tank"
module).
22
TRADITIONAL WELL WITH DEFECTIVE METALLIC PUMP REPLACED BY AN EMAS PUMP,
AND REMOTE MANUAL PUMPING Many water sources do not require the expensive search for new sources, they can be simply and
cheaply improved. A typical example of this is a working well with a broken metallic pump.. The
function of the pump was limited to providing a better quality of water. When the pump was
broken, the users uncovered the well and used buckets to access the water, as they had done before
installing the pump. The rehabilitation and maintenance of the pump were too expensive for the
community, so they were not carried out.
However the diagram below shows a different solution. Water is delivered from the pump, by
manual pumping direct to the house owners kitchen tank. Here the water at the house makes life
easier, no need for the tedious daily transport of water, and the water has been given the added
value of supplying the needs of the consumer in his/her home, that is, a domestic supply.
This added value means that the
maintenance of the individual micro
supply is both sensible and cheap, it
can also be carried out by the
individual user, and the house owner
is willing to spend time and money
maintaining the added value.
An essential piece herein is the EMAS
pump, which the user himself learns
how to set up and then knows how to
repair it. The pump has a low cost,
and all necessary materials can be
obtained at the local hardware store.
Note: To protect the air chamber and
the check valve, a bottomless
'pitcher' is used. Experience has
shown that the 'pitcher' protects the
pieces better than when using a small
case. Besides, vehicles do not run
over it, because the 'pitcher' looks
like a big stone.
23
SETTING UP AN EMAS PUMP IN A WELL WHICH HAS NO ANTECEDENT OF A FORMER
PUMP There are many fine open working wells which have been excavated by hand and covered with
stones or bricks. These wells have cost a lot of money and effort to build, and are therefore cared for
with devotion. However, due to their manner of construction, water can only be drawn using
buckets. In drawing the water the buckets carry dirt and dust into the well, thus acting as a source of
contamination. Further, the fact that the well is open means wind-blown dust can enter. This is not
conducive to good hygiene
If we were to offer to the owner, in an effort to
improve the quality of the water, to shut the well with
concrete and install the EMAS FLEXI pump, what
would his/her reaction be? Would we be surprised if
he declined? Would we be surprised if s/he
questioned the durability of the pump? Also, if the
well is closed and the pump fails, will it not be
impossible to draw water with buckets, thus rendering
the well useless? These are logical and real concerns
and therefore the owner will not authorise the work.
However, the case is quite different were the proposal
to set up the pump is such a manner as to enter the
well laterally. This requires a small aperture in the
jacket of the well and leaves the well open for any
eventuality which may occur in the future.
The procedure is as follows:
Dig a hole of approximately 1.50 metres deep next to
the well, down the jacket of the well. With a chisel,
open a hole in the wall of the well, and pass a PVC
pipe (1 1/2" - 2" sanitary) through the aperture;
this will serve as a casing for the pump. At its end,
the casing has a sharp point that will be nailed at
the bottom of the well and thus make the pipe
steadier. About 30 cm above the well level, the casing is drilled to allow for water intake to
the pump. If the well is deep, the casing must be fastened every 3 - 4 metres. Next the
excavated hole is refilled. It is most important for the material to be sufficiently compact,
mixing earth and water. For a platform, an old tire will do. Finally, arrange the pump in the
casing. The well is covered provisionally with wooden boards and plastic thus avoiding
windblown dirt and dust entering the well.
This set-up allows the use of only one EMAS pump, because it is built with flexible materials which
are not affected by a slight bend or curve.
24
SETTING UP AN EMAS PUMP IN A WIDE WELL DRILLED, OR IN AN EXCAVATED LARGE
WELL Where a drilled well with a broken metallic pump already exists, the EMAS Flexi pump can be used
to replace it. As the FLEXI pump has no bolts etc to be fastened, it must be adapted to the existing
well hole.
The easiest and quickest solution is to make a conical wood
plug with a hole drilled in its middle, this hole being the
diameter of the cylinder. Wedge the plug on the well hole
and set up the pump through the hole of the pressure plug,
using tyre strips to ensure the plug is tight fitting. It is
advisable to use dry wood for this plug as dampness will lead
to swelling, thus making it tighter. This will prevent polluted
water entering the well. It can be difficult to perforate the
plug without a vice: an alternative is to carve two halves of a
plug and to join them to form the plug.
A concrete plug can also be used. For this it is advisable to
cast a guide pipe for the pump at the middle part of the
plug, and let it stand out about 15 cm ( a 1 1/4" pump
needs a 2" guide, and a 1" pump needs a 1 1/4" guide).
The conical shape of the plug is compressed inside the
well pipe and thus the hydraulic seal is obtained. When
plastic sheets are arranged around the plug, the sealing is even better.
Excavated well
When a FLEXI pump is adapted to an excavated well, a
round shaped concrete tile is cast, and at its middle part
(or at one of its sides) you arrange the guide pipe. The
guide pipe can be of thick PVC or galvanized iron, and it
must hold tightly to the cement. For this purpose, small
bars or beams can be used, or grooves may be cut in the
pipe. The pump is introduced into the guide pipe and
fastened with tyre strips.
When the well is deeper than 4 metres, the pump, or the
pump casing should be fastened on stands that go across
the well every 2 - 3 metres. If the sharp end of the pump
moves in the well, the water will be turbid. In order to
prevent this, the sharp end should be pressed down inside
the bottom of the well. The intake aperture/hole should
be about 10 cm above the ground level
25
THE HYDRAULIC RAM
What is the Hydraulic ram?
A knowledge and understanding of the hydraulic ram is important for well drillers and technicians
working in the area of hydraulics.
Hydraulic rams are often the cause of burst water pipes as they can increase the pressure in a pipe
by up to 20 times normal pressure. Water running in a pipe can be compared to a train in motion. If
the train hits an obstacle, even at reduced speed, the collision is violent and causes damage
because the train cannot brake or stop suddenly. The same thing happens with water when
it is running in a pipe and is suddenly stopped.
Another example of this occurs when water and air are mixed coming out of the tap. This is often
referred to as 'coughing'. It occurs because air can be compressed (as in tyres, a compressor, etc.)
but water cannot be compressed. Therefore, air has different fluid properties than water. Under the
same pressure a given volume of air can be evacuated from a fixed diameter pipe/aperture, faster
than an equal volume of water. When air gets into a water pipe, air pockets are formed and they
compress depending on the pressure. When the water and the air exit from the faucet/tap, thus
discharging the pressure, the air leaves the pipe at a much higher speed than the water. Therefore a
depression is formed in the piping, behind the air, and this "vacuum" causes all the water inside the
piping to accelerate. When, at a higher speed, it reaches the outlet orifice, not all of it can pass
through. Since water cannot be compressed, pressure increases for a few seconds, until the whole
water column is held back inside the piping and it reaches its normal pressure.
The same thing happens when a stop cock is suddenly shut. Pressure is increased, because water
running inside the piping cannot stop suddenly.
The longer the piping, and the greater the speed of flow speed, the slower the stop cock must be
shut. The air in the water piping caused a hydraulic ram stroke.
26
The hydraulic ram
The hydraulic ram utilises the pressure stroke that occurs when a water column in motion is
suddenly stopped. This refers to the column of water in motion inside the pipe, only.
The hydraulic ram can be thought of as a pump driven by the energy of the water itself in motion. A
ram is easy to build, it is durable and does not consume fuel. However it pumps only a small fraction
of the water it uses (3 - 10%).
The hydraulic ram takes advantage of the principle that a water column in motion cannot be
stopped suddenly. Applications for the hydraulic ram are limited, but in these applications the
increase in pressure can be very useful
What are the main applications of a Hydraulic Ram?
It can be used to pump water up from an irrigation channel: it can be used to pump upwards from a
watershed with good flow and to pump water upwards from a river.
How does a Hydraulic Ram operate?
A ram requires impulse tubing/piping, a valve that can be regulated by being shut when a certain
flow exists and then opened again when the flow stops. An air chamber and a check valve are also
required.
When a cycle starts water is still (not in motion) inside the piping (this is marked D in the diagram
below). When there is no flow the weight acts to open the operation valve, C. This starts the water
flowing/running in the impulse piping and it passes out through the operation valve.
27
As the outlet is free, water continues to accelerate to such a point that the stream raises the disk of
the operation valve and shuts it instantly. The water column that was running inside the impulse
piping cannot stop suddenly, and therefore produces a pressure much higher than that of the slope.
This pressure opens the check valve (B) in the ram, and allows a good stream to get into the pressure
chamber (A). The water column stops, the check valve is shut, the operation valve opens, and a
new cycle begins.
Parts of a hydraulic ram
Slope : In order to operate a hydraulic ram, a 1 metre slope is sufficient , although a greater slope
can be used. Where the slope is more pronounced, water has a higher acceleration in the piping, it
runs faster and intervals are more frequent. Therefore, the volume is greater.
Impulse piping : The intensity of the stroke and the pumping pressure, depend on the impulse
piping. The longer this piping is, the more the volume of water accelerates, and thus, when closing
the operation valve, the stroke is harder.
If the piping is long and has a slight slope, it will require several seconds until the watercolumn
reaches sufficient pressure/ impulse to shut the operation valve. Therefore the longer the impulse
piping is, the harder the stroke will be; the water will be pumped higher, but the intervals will be
longer, accompanied by less efficiency and more wasted water through spillage. Also, costs will be
higher due to the costs of the extra piping.
Operation valve
This valve can have many shapes, and is not difficult to set up. It is very important that it fits the
dimensions, and that it allows the total volume of water to exit, while it is accelerating. It must also
shut firmly.
The valve should open automatically once the pressure has gone down to the hydrostatic value.
Therefore it must be adjustable. Generally weights or springs are used to lower the disk, and thus
oppose the hydrostatic pressure (resulting from the slope).
Check valve
The check valve can be of the type available at the local market, or it can be built onsite like the
FLEXI pump foot valve. However, it is wiser to purchase it, to guarantee that it plugs firmly.
Air chamber or pressure chamber
The function of the air chamber Is to transform into a continuous stream the pulsating stream that
exits from the hydraulic ram. As a result the friction inside the piping will decrease, and the pumping
yield increase. When the stream of water enters the air chamber, it cannot be ejected instantly.
By compressing the air in the chamber like a spring, the water present in the chamber can be
ejected, but only the volume in the chamber and only after the intake from the hydraulic ram has
stopped. Air chambers are not only used for hydraulic rams, but also for piston pumps, as well as for
all kinds of EMAS FLEXI pumps, most commonly when pumping water over a distance. All air
chambers need adequate maintenance. Pressurised water has the property of absorbing more air
than non-pressurised water. Therefore after some time, air inside the chamber decreases, and it
28
must be replenished. Depending on the
characteristics of the system, air in the chamber
must be increased at given times. For this
purpose, every chamber has a pneumatic valve.
How to set up a hydraulic ram
The design shows how to set up a hydraulic ram
using ordinary materials. The model is 1 1/2". On
a nipple of a 2" and 20 cm length piping, weld a 1
1/2" short nipple, to be connected to the impulse
piping. At the opposite end, a 1/2" nipple is
welded, to which the check valve is screwed. A
stroke disk can be made from a 5 mm plate or
from a piece of spring. Otherwise an old engine
valve can be used.
The connecting rod is welded to the disk, at right
angles. By reducing a 2" pipe to its inner diameter
the valve seat can be made as can another tube of
1 1/2". To guide the connecting rod a small beam,
perforated in the middle, is welded. A 1 1/2" bend
forms the outlet. On its upper part, it is
perforated allowing the connecting rod to pass. Its
operation is controlled by means of a lever with
weights.
To fix the stroke disk on its seat, the upper part of
the connecting rod is attached to a drill and turned.
At the same time, sand is distributed between the
disk and the seat. Once the disk has been fixed to
its seat, it is plugged firmly and shut. It is important
to leave a space of 1 1/2" between the disk and
the wall of the 2" pipe.
29
HOUSEHOLD INSTALLATION Fetching and carrying water from a distance to the home is a "a necessary evil".
However, when water is available in the home from the kitchen tap or from the shower, it has added
value, and is a symbol of added status. This status is based on the fact that the water supplies
comfort, saves time and also promotes and increases personal hygiene. With this added value the
water assumes an importance such that the user is willing to use scarce economic resources to
repair and maintain the water supply.
Therefore, this kind of supply can be said
to be truly sustainable. Costs are not high
and the user assumes the expenses for the
individual installation of each household
facility.
Household installation is an integral part of
the EMAS concept, and it has been made
possible due to the EMAS pump which
pumps water from its source up to an
elevated distribution tank.
A water installation can be installed with
many de luxe applications (such as a
jacuzzi for the upper class), but the basic
demand in rural and suburban
environments/communities is to have
water in the kitchen, and if possible a shower (in places with warm weather).
The ferro-cement tank (pitcher; "cantarito" in Spanish) is arranged on 4 solid wooden supporting
beams about 2 metres heigh. The distance between them should not exceed 80 cm, so as to
facilitate a plastic sheet around them which can be used as a screen when taking a shower.
The laundry table should be set at a height of 80 cm , and the faucet 1 metre high. The drain pipe
can have a diameter from 3/4" to 1 1/2". Experience has shown that a 3/4" polyethylene hose is
sufficient, and also inexpensive. For the household installation it is advisable to use PVC 1/2"
pipes, with folding or coiled accessories. Self built accessories will also be useful, as there is not
much pressure in this system.
30
HOW TO ELIMINATE IRON
A - physicochemical treatment
Iron is eliminated by oxygenating/aerating water. In potable water treatment plants, waterfalls,
compressed air or other mechanisms are used to put water in contact with air. Water is then left to
settle for half an hour, so that a flocculant may be formed.
The flocculant settles at the bottom of
the container, which is funnel shaped,
and the water passes through a sand
filter. There the remaining iron is
removed.
To obtain a colourless water, with no
iron flavour follow the procedure
below. If waters are too soft (with no
mineral content) and with low pH,
flocculation does not proceed
satisfactorily. To assist flocculation, the
pH is increased, by pouring in liquefied
lime.
B - biological treatment
Reddish spots of rust that can be seen
by the riverside and if examined they
appear like loose algae. In fact they are
colonies of iron bacteria which take
advantage of the energy potential
between iron in solution, and iron as
rust. However after running over a certain distance, the colour disappears and the water looks like
any other water. What is happening is the biological treatment of the iron. Something similar can be
carried out at household level to remove the iron content. The model shown over has been tested,
with excellent results. It is inexpensive to set up, its maintenance cost is almost nil, comprising of a
curtain belt that must be cleaned only once or twice a year. For the curtain a polyester cloth, or
simply a strip from a quilt can be used. The tank is located on top and at the bottom, are the
'pitchers'. The more iron the water contains, the slower the rate of dripping will be. With a strip 1,4
metres long and 20 cm wide, approximately 150 litres per day can be treated. Instead of a filter use a
synthetic cloth as strainer (or another strip from a quilt), arranged on top of the receiving 'pitcher'.
The household installation usually has two faucets : hard water runs from one of them, for usage like
dishwashing, etc., and the other one with water which has no iron content, used for cooking,
drinking and washing clothing, since water with iron content leaves stains.
31
BOTTLE FILTER AND EMAS FILTRATION PLANT
Surface water from a pond, cofferdam, lagoon or river is not potable. To make it potable, microbes
must be eliminated using chlorine or another disinfectant. Chlorine is not very effective in turbid
waters, and moreover it also has an unpleasant flavour.
Therefore the water should first be filtered. The "Popular Filter" described below is easy to build
using an old plastic bottle; it costs nothing is very effective, its weight does not exceed ½ kilo, and
due to the transparency of the material, maintenance is simple.
32
Materials Required:
A used plastic bottle, approximately 100 grams of polyester fiber, or a piece of polyester cloth, cut in
strips, or where there is no cloth or fibre available, nylon stockings (lycras) can also be used. Use a
piece of porous sponge as pre filter.
How to build the filter :
Cut the bottom of the bottle with a knife or scissors. Then, with a strip of polyester cloth, make a roll
the same diameter as the bottle, and put it inside the bottle, pressing it . The water to be filtered
passes through the cloth, and the dirt is retained. When waters are very dirty, the filter tends to
block quickly. In order to increase the capacity, arrange on top of the roll a round shaped sponge
which will absorb the larger particles. To clean the filter, simply hold the roll in its place inside the
bottle, and blow some air through the bottleneck. Instantly the air will be ejected, mixed with dirty
water. The sponge must be washed separately.
These filters can also be improved. When water has an unpleasant flavour even after it has been
filtered, odours can be eliminated by letting water pass through a carbon filter.
For carbon filtering, it is most important for the water to be pre filtered. This is accomplished by
using two similar filters separately. The carbon filter is slower, but it considerably enhances water
quality. In order to have "super filtered water available at all times, this combination of slow sand
filters is mounted on a wooden or iron frame. It is very important to maintain these filters
moistened, so a microbial' film can be maintained on top of them. This film increases the retention
capacity of the filter. Firstly water is passed through the simple fibre filter; usually this will be
sufficient. If water continues to have an unpleasant flavour, then change the bottle and let it pass
through the carbon filter.
With a small dose of chlorine or another disinfectant the water will have the same flavour as a
municipal supply. After half an hour, the water will be potable. Remark : our health will not be
affected if the chlorine flavour is rather intense. Disinfectants are not insecticides, and their raw
material is salt and water.
33
EMAS MANUAL DEEP DRILLING (WASHING) This drilling method can drill to a depth of 100 metres in soils of fine material which do not contain
stones. The drilling diameter is only 2 inches. The average yield of these EMAS wells is 1 litre per
second, that is to say 3600 litres per hour.
In Bolivia, the price of each metre / well including water jackets and the pump, is about 6
Euros/Dollars.
This drilling system is also very useful in soil survey work, for example when searching for a weak
aquifer and subsequently excavating manually a wide well. It is also useful for setting up
foundations, highways and in mining.
This system can be used when working with aquifers of very fine sands without the risk of
introducing sand into the well, and thus damaging the pump. For the filter, instead of gravel, we use
a sleeve of synthetic cloth with different texture. In order to achieve an adequate activation using
this synthetic cloth, the well is activated by means of a reverse ram, and not - as usual - with
compressed air. This ram allows the extraordinary pressures and depressions necessary to initiate
flow in the well.
Three people can carry out the drilling works. Usually they progress 30 metres per day. The weight
of all the equipment does not exceed 200 Kg; therefore it is suitable for places where access is
difficult.
34
Tools needed :
- A 4 metre high derrick made of iron for construction. The derrick operates as a crane to introduce
and remove the drill pipes, and as support for balance. The derrick is fastened with 4 tension rods.
Also a lever with its shaft is required, a small stick to pull the rope and one or two pulleys and a
resistant rope .
- 60 metres of drill pipes = 20 bars, 3 metres long, and two pieces 1 metre each, with 1 inch
reinforced nipples. Also, a bit in place and another spare. One or two holders, 7 metres of 3/4" hose,
and a mud pump.
- Also required are a pipe press to fasten the drill pipe when screwing and unscrewing its pieces, 2
pipe wrenches, a piece of wire mesh to sift mud, two buckets and a steel brush.
Person A is in charge of raising the pipe with the bit between 10 and 40 cm, and drops it as strongly
as possible, so that the tooth of the bit is embedded in the ground. Usually about 20 strokes per
minute is possible. The pipe/bit can be raised with a lever or with a stick and rope that goes through
the pulley at the derrick. When starting use the pulley, and after about 10 metres, the lever. The
deeper the well, the longer the lever should be.
Person B is in charge of drilling. Once the tooth of the bit is embedded in the ground, this person
turns it around once; thus the tooth tears away the material and mixes it with the drilling liquid.
Person C pumps liquid into the well, by means of a manual pump, in order to stabilize the walls,
maintain sand grains afloat and expel the drilled material. The liquid, which consists of water and
clay, is ejected from the pump, passes through the hose, goes into the pipe though the holder, goes
down inside the drill pipe, is then ejected from an orifice at the bit, mixes with the drilled material,
and goes up - somewhat thicker - to the upper hole and falls down again into the mud well, and a
new circuit begins. It is most important to adapt the density of the drilling liquid to the material of
the soil being drilled.
When clay is being drilled, water is used, and when sand is being drilled, you need heavier water.
Usually this liquid forms itself when drilling an argillaceous soil, but there are very sandy places
where one has to prepare the mud, manually mixing clay with water. The EMAS system does not use
bentonite.
Once a depth of one metre has been drilled, another 1 metre pipe must be added. When a depth of
2 Metres is reached change the two 1 metre pieces, for a pipe 3 metres long. In the drilling hole, 3
metre pipes only are used until the drilling is over.
The Drill pipes are 3/4 inches galvanized iron piping with 1 inch screw thread nipples as
reinforcement.
When the pipes have perforated about 4 metres into the aquifer, well washing can commence.
Clean water is injected into the well, not muddy water. Water from the bottom of the well is
displaced upward until this water runs clear. When the injected water runs clear from the bottom of
the well the well can be considered clean. This is followed by removing the pipes used for drilling,
using the pulleys as cranes, and the press to fasten them when unscrewing. The well consists of the
35
filter and the pipes of the water jackets. Usually, 1 1/4 - 1 1/2 inches pipes are used, whether
sanitary pipe, or class 15 bar PVC. The filter is a pipe of the same water jacket, in which grooves are
cut with a saw. To prevent sand from penetrating into the well, arrange a synthetic cloth sleeve on
the grooves.
Once the drill pipes have been removed, the
well piping is put in, first embedding the filter
with its plug, and then the piping jackets. The
well is washed for a second time, by
introducing a 1/2" pipe to the jacket. Pumping
clean water into the well, the filter cloth is
washed and remainders of clay which may
have caused blockages when the filter was
introduced to the well, are removed. A bucket
of sand is then introduced into the well, in
order to seal the filter, and to fill the space
between the wall of the aquifer and the filter.
It is worth mentioning here, that many
different techniques exist in EMAS drilling.
Over the years, drillers have learnt to cope
with different soils which are specific to their
regions. There are several kinds of bits,
designed for different soils. For cemented and
very hard soils, sharp ends with diamantine
are used; for sand and clay, classic forms are
made from sharp end tooth steel together
with lateral beaters.
Sometimes a check valve is arranged on top of
the bit, and the work is performed in reverse, pouring clean water into the hole, and removing the
material through the drill bars. This is usually done when the phreatic level is too low and cemented
material is present.
When a spurting aquifer is encountered, the treatment differs even more . When an unreliable
aquifer is reached, then provisional tests (with the reverse ram) are required to determine drilling
progress. Sometimes this can require a long filter reaching almost to the top. When well production
is very weak and the phreatic level is not too deep, such that the well does not allow normal
pumping, a compensation tank may be placed below this level, manually excavating around the
drilled well.
The last operation when drilling an EMAS well, is to activate it. While drilling, a layer of clay may
have adhered around the sand of the aquifer. This clay can obstruct water inflow to the well, and has
to be removed. Usually, compressed air is injected down to the bottom of the well, so that its strong
bubbles may drag down the clay. A synthetic filter would require an engine and a compressor and
may not prove very satisfactory.
36
The system of the reverse ram is simpler and much more effective. A 1/2" pipe is introduced into
the well, with a check valve at its bottom. The check valve consists of the piston valve of an EMAS
pump which can be manufactured locally. But the motion of quickly pulling the pump in and out,
about 40 cm, the effect of a reverse ram may be obtained, and the water flows upwards inside this
pipe. At the same time, at the bottom of the pipe, strong pressures and depressions are formed due
to the ram. As a result the clay that has adhered to the wall of the aquifer passes through the sand
and the cloth, towards the well, due to suction from the reverse ram. Different materials may be
used to form the platform for an EMAS well. An old tyre is almost indestructible, and is cheap
37
THE EMAS DRILLING SYSTEM USING SUCTION Whenever thick sand and small stones or pebbles are encountered, resulting in difficulties in normal
drilling (washing), then the drilling method may be changed, and the suction system used. As long as
the pebbles do not exceed the size of a grain of corn, the components used in the classic EMAS well
can be used by simply adapting a check valve below the holder. However if a pebble size greater
than 2 cm is found, then bars of a larger diameter are required together with a larger valve. If using a
normal EMA system (washing), the drilling liquid should be strongly thickened to be able to carry
pebbles. This is not always possible.
Another method of extracting thick materials is by increasing the flow speed of the liquid; this can
be accomplished by using the suction
system, as the flow area is smaller. In
the washing system, the liquid is
pumped by the bar up to the bit, and
then it goes upwards, with the
material pulled out between the bar
and the well wall (the well overflows).
The suction system is the opposite; in
it, the liquid goes downward as the
well is drilled, but it goes upward with
the material pulled out from inside
the bar. The well being drilled must
always be full of liquid; thus the
depression of the suction only needs
to surpass the height between the
ground and the holder. To initiate the
suction vacuum, the valve has to be
lubricated with drilling liquid. The
advantage of this technique is that no
pumping is needed, since the liquid
goes upward itself, by the motion of
the bar. Also, it does not need much
control with regard to the quality of the mud (drilling liquid)
When deeper wells are being drilled, after several days work , the mud pump must be used when
introducing the drilling bars again. In soils of fine material, this system allows depths down to 100
metres (generally in combination with the washing system).
Another variant of the suction drilling is a vacuum produced by the mud pump itself. Instead of a
sifter, a suction hose is connected to the mud pump and a small liquid container at the upper part of
the cylinder, to prevent the pump from sucking in air. The other end of the suction hose is
connected to the sedimentation tank. The sedimentation tank is attached to the drilling bar, and it
also serves as the holder
38
When pumping, a vacuum is
formed at the pump cylinder and
this is then transmitted to the
sedimentation tank through the
suction hose. This vacuum
continues downward inside the
bar until it reaches the bit, where
it sucks the material pulled out,
upwards inside the bar, until the
material falls into the
sedimentation tank. There the
heaviest particles settle, such as
pebbles and thick sand. The liquid
overflows at the outlet, and to the
well being drilled. To maintain
maximum suction it is important
that the drilled well is kept full of
liquid.
If a big stone obstructs the sharp
end of the bit, it can be broken up
and set apart, using a plain iron
spear, which is introduced into the
drilling bar by the unblocking orifice.
It is not necessary to remove all the drilling bars in order to unblock the bit. When pebbles have a
diameter larger than that of the drilling bar, larger bars can be used. However, this involves a change
to the standard type of drilling bar, and the increased weight can cause transportation problems.
This system has its limitations, it is slower, is dependent on the soil granulation, and cannot cope
with large stones. The depth is also limited to about 30 metres.
39
EMAS MULTIWELL EMAS technologies are both appropriate and inexpensive and are not only useful for individual
dwellings, but can also provide a network of potable water for the community.
The first step in community work is usually a survey. This involves calculating the investment
required, the depth at which the water is
to be found, the quality of the water,
whether the aquifer provides a good
volume and most importantly the depth of
the static and dynamic levels of the
proposed well.
If the aquifer is good but quite deep (more
than 20 metres), and the static level is
high (about 6 metres) and also the first 15
metres of earth is argillaceous and
compact, then the most adequate solution
is the EMAS multiple well. The suitability
of the EMAS Multiwell applies where the
community is distant and access is
difficult, factors that increase considerably
the cost of a motorized drilling.
The first step is to drill a deep exploration
well. Where the results are positive, a
series of other wells can then be drilled in
a circle. The distance from one well to the
other must not be less than one metre. In the centre of these a further well is excavated with a
traditional lining, down to 3 - 4 metres below the static level. As the material is waterproof (this data
is gathered from the deep drilling) there will be no problems with intense water leakage when
excavating. Once the manual excavation of the wide well has finished, arrange a forking of the
jackets to the excavated well. As a result each well drilled drains its water to the large well, and
together they quickly fill it up to the static level. The last step is to set up a motorized pump that
pumps water from the excavated well. Its volume is approximately the volume of the first well,
multiplied by the number of satellite wells.
Another great advantage of this method is that an industrial pump can be set up, with a higher yield
than pumps for wells drilled with several rotors. This will show a considerable saving of energy.
Another advantage is that all the work has been performed by the community.
Other benefits are that the investment and operation costs are low. The community identifies itself
with the Work and take ownership of the well. There is less dependence on spare parts as industrial
pumps are almost universal. The system encourages similar works, because people do not need to
40
beg from institutions that provide motorized drilling services . In summary the same volume of water
is obtained as from a motorized drilling, but for a much lower cost. Operational costs are also lower.
EMAS DESIGN FOR RAINWATER HARVESTING In areas where there are no water resources available, such as a spring, well, river, brook, lake,
irrigation channel, etc., the only solution left is Rainwater Harvesting. This type of system is not new.
It was used over 2000 years ago by the Israelites to supply cities such as Mazada located in the
desert. Few places in the world are unsuitable for rainwater harvesting.
The roof
Roofs with metallic plates, roof tiles, cement fibre and reinforced concrete serve to collect water.
Metallic plates have the advantage that they do not need a significant gradient, and they do not
absorb water, like roof tiles do.
Roofs made of straw or branches/leaves are not appropriate, because they impart an unpleasant
flavour and colour to the water.
Water volume
With an annual precipitation of 20 cm, a figure which is classified as semi-desert, 20,000 litres fall
on a 10 x 10 metres surface.
If we take a family of 5 people, and an average consumption of 10 litres per person/day, then the
daily consumption is 50 litres.
Dividing 20,000 litres by 50 litres per person we obtain 400 days of water supply, that is to say,
more than one year’s supply.
The water volume available depends on the area of the roof, and on the volume of rainfall. In places
where rain is scarce, a larger roof is needed than where rainfall is abundant .
41
The formula of water volume in litres is :
Length x width of the roof (in metres) x the amount of annual pluvial precipitation in millimetres :
� � �. �. �
Many places in Latin America have rainfall of about 500 millimetres per year. When the house is
small, 5 x 6 metres (that is to say 30 square metres), with 500 mm annual precipitation, it receives a
rainfall of 15,000 litres on its roof; this is a sufficient amount for a family of 5 .
Collection
Roof gutters are used to collect water from the roof. Roof gutters are made of different materials
such as PVC, zinc plates, bamboo, etc. It is important for the roof gutter to be able to cope with
torrential rainfall. To prevent obstructions due to leaves, the roof gutter must be cleaned
periodically.
The filter
Little birds soil, leaf fall and the wind deposit dust on the roof. If these particles get into the cistern,
they rot and emit bad odours. At the same time, many germs are formed which are not harmful for
humans, but are indicators of pollution.
Therefore these substances must be retained by a filter. Experience
has shown that a fine strainer is adequate. As a filter box, a pitcher is
used with a 1 – 2 inch outlet, depending on the size of the roof. As a
filter screen, the cloth of a synthetic blanket can be used, sown into
the shape of a bag, with a round-shaped bottom. On the upper part at
the fold, an iron ring or a galvanized thick wire is arranged. The ring
must have a larger diameter than the pitcher's nozzle, so that the bag
hangs in the tank but does not
reach the bottom.
It is advisable to clean the bag
every 3 months. Almost all
traditional cisterns have no filter.
To keep out pollutants, the first
part of the rainfall is deflected; this
first flush of rainfall generally
contains most of the garbage.
However, there is always a certain
amount of dust and leaves inside
the cistern. If the first flush device
is not operated correctly the water
may be spoiled and the cistern
emptied.
A roof impregnated with smoke imparts an unpleasant flavour to water; therefore it is important
that the kitchen has a tall chimney, or else choose a roof that is not exposed to smoke. Results of
42
recent studies from Paraguay with regard to the abrasion of heavy metals occurring in zinc plated
roofs are that practically no traces are left, and that the risk is minimal.
EMAS Cisterns
Among the many shapes and types of cisterns available, the EMAS cisterns excel because of their
ease of construction, low cost and life span. They are underground tanks coated with a thin layer of
cement mortar and made waterproof with a pure cement whitewash. On average, their volume is
4000 - 8000 litres; generally 2 - 3 cisterns are built for a house when it is supplied only from pluvial
waters. Normally an EMAS pump is used to pump water up to a ferro-cement tank to be distributed
at the dwelling.
Distribution to the cisterns (underground tanks)
Water can be conveyed from the roof to the filter through a 1 1/2 - 2" sanitary pipe according to the
size of the roof. From the filter to the cistern, a smaller size will suffice, since the volume of the filter
pitcher compensates short increases during heavy rainfall.
To connect the cisterns, follow the directions shown in the drawing. It is best to fill only one cistern
every time, and close the outlet of the other cistern with a plug. By means of the connection shown,
the other one can be connected in a few seconds, pulling out the plug and switching the bend. It is
advisable to arrange a wire mesh at the external sharp end of the overflow, to prevent insects and
mice from getting inside.
Exceptions for the interpretation of bacteriological analysis in pluvial
impounding
As we are dealing with rainfall harvested from the roof of a house, and most users do not use
chlorine to disinfect water, it is more than probable that germs will be found in the water during its
storage. When the quick filter is not used correctly, organic matter may get into the cistern and form
a sediment that slowly mineralizes, giving bad flavour to water and, most of all, leaving many germs.
Even using the filter correctly , it is a fact that after a fall of rain, captured rainfall may contain germs
coming from the roof which may originate from the excrement of little birds, small lizards, flies, etc.
The WHO (World Health Organization) standards state that potable water must not contain a
determined number of micro-organisms, it must not have E.coli or coliforms, but the base for all
these requirements is that potable water must not be harmful for health.
With rainwater harvesting, without the use of chlorine one cannot achieve the above mentioned
indicators (few germs, no E.coli or coliforms), but it can be guaranteed that the water is not harmful
to health, since those indicators themselves are inoffensive and practically no pathogenic pollution
exists, since animals with potential illnesses for man do not excrement on roofs (big mammalians).
Therefore, other parameters must be used when interpreting a bacteriological analysis of pluvial
waters stored during months in underground cisterns (A point to be evaluated in the pilot project).
43
EMAS CISTERNS Among the many shapes and types of
cisterns available, the EMAS cisterns
excel due to their easy construction, low
cost and life span. They are underground
tanks coated with a thin layer of cement
mortar and made waterproof with a pure
cement whitewash. On average, their
volume is 4000 - 8000 litres; generally 2 -
3 cisterns are built for a house when it is
supplied only from pluvial waters.
Normally an EMAS pump is used to pump
water up to a ferro-cement tank and to
be distributed at a dwelling.
Multiple uses of a cistern
There are multiple uses for the EMAS
cistern. It may serve as a stand-by
reserve for a well that conveys water
only during the rainy season. It may serve
as a deposit in case the water supply is
irregular. When salt water or polluted
water exists in a well, and where it may
still serve for washing, bathing or other uses, rain water stored in a cistern solves the problem of
water for drinking and cooking. Several cisterns, in classic EMAS shape, serve to store pluvial waters
which are the only form of supply. The cistern can also be used as a treatment tank, for instance for
the flocculation of turbid waters from a ravine flow.
Sometimes a cistern can be used to store sewage waters which are subsequently used for irrigation,
after being treated in septic chambers.
Building an EMAS cistern of vertical Design.
The diameter of the excavation should be 0.8 metres, for a depth of at least 1 metre in firm soil.
After this the diameter is enlarged to 1.4 – 1.8 metres. The reason for the reduced diameter at the
neck of the cistern is due to the cover. A large cover, with a 1,8 metres diameter is expensive to
build, and difficult to handle. Instead, a cover with only 1 metre diameter weighs less, is easier to
build, and it is quite inexpensive because of its arched shape, given that it uses few iron bars.
The depth of an EMAS cistern practically has no limit, but usually it is as deep as the length of the
ladder, 3 - 4 metres on average. Once the desired depth has been reached, the excavation of the
bottom should be shaped like a half ball. This shape allows the sediments settle at one point only,
thus facilitating removing them with the pump.
44
The curbstone
When the excavation is finished, the
curbstone is set up. However, before doing
this the intake and overflow piping should
be set up. For a roof up to 50 m2, a 1 1/4"
pipe will do. A plastic millimeter screen is
tied to the overflow pipe to prevent insects
or other animals from getting into the
cistern.
The foundation of the curbstone should be
arranged around the cistern's opening,
about 30 cm deep. This is done using
stones and mud, or only mud. On the
moistened mud a cement layer of about 3
cm is set, to make it solid and waterproof.
Mud cakes
When the curbstone is finished, start setting up the mud cakes. Their function is to form a clean and
solid layer, on which the cement whitewash can be put. Only a pure cement whitewash can be
guaranteed to be waterproof. Increasing the thickness of the mud cake (except at the bottom of the
cistern, where the ladder is arranged) only increases the cost, but does not improve the quality of
the cistern. The full thickness of the mud cake is about 2.5 cm. A thicker wall an iron screen or
chicken wire may be used and though more material will do no harm, it is not necessary. None of
these would resist a telluric movement (of the earth). A thick wall would also crack. This has been
learnt from the use of traditional cisterns and tanks with walls of brick or reinforced concrete.
When excavating a stony soil, and holes remain where stones have fallen, it is preferable to cover
them with mud made of the same earth. It is better to use slightly dry mud. In preparing a cement
mortar with fine sand, the proportion may vary between 1 : 4 and 1 : 5, according to the sand
texture. This mortar is used to plaster the first coat directly onto the moistened earth. Its thickness is
approximately 1.5 cm. Once this mortar has been exposed to the air and dried, the second coat is
added, made up of a proportion of 1 : 3. The second coat is thinner than the first coat.
It is important that all the plaster works be performed without interruption which means not letting
some days go by between one plastering and the next, or between whitewashing, because then the
cement will not hold. During the second plaster, the wall is polished, but it does not matter if it is not
perfectly symmetrical, straight or flat. For this task, the use of a slipper or a house shoe (flip flop) has
proved very practical. Those who are not well acquainted with the use of a trowel should use rubber
or oilcloth gloves and set the mortar manually. At the end of the plastering, the case pipe is arranged
for the pump, with its plug.
Pure cement whitewash
When the plastering is finished, wait about 12 hours to set the first whitewash layer. It is most
important to always cover the cistern mouth with plastic when not working, to prevent the cement
from drying. Whitewash is a mortar of pure cement and some water which looks like toothpaste. It is
45
laid on the wall with a brush or a thin broom. Care must be taken when laying a whitewash because
it makes the wall waterproof. Even the smallest holes or pores must be covered.
Usually two coats are laid. It is said that 70% of cisterns built by junior technicians leak water
because the whitewash was not carefully laid. The inlet hole of the case is perforated with a knife at
floor level, but only when the cistern is finished and the cement has hardened. The drilling must
have a diameter of at least one inch. A little pit at the deepest point of the cistern helps to evacuate
even the last drop of water. It is advisable to wait at least 5 days before filling the cistern, to prevent
the water acquiring a cement flavor.
The cover
There are many different shaped covers. EMAS casts its covers arched and vaulted. For a mould, a
small hillock made of earth and covered with plastic or paper is used. The height of the arch is one
fourth part of its diameter. This shape allows great resistance to pressure on its upper part, and it is
inexpensive because it uses no iron bars, except a 1/4" ring near its outer edge. To be able to pick up
this cover, which is quite heavy, two holders are cast, tied to the 1/4 iron ring. For a 1 metre
diameter cover, cement must be 5 cm thick ( the larger the diameter, the greater the thickness). For
its outer mold, a 1/4" x 2" platinum is used, or simply stones, earth, etc. on its edge. At the center of
the arch or vault a short 1 1/4" pipe is cast, of about 20 cm length. This pipe is used to control the
level and volume of water, and must be always plugged with a stopper made of the same PVC pipe .
Usually the cover is adjusted with mud on the curbstone. In exceptional cases a base of synthetic
material may also be used ,by forming a ring of cloth or rolled up plastic. We do not recommend
adjusting the cover directly on the curbstone, since it may not be steady and may then brake.
Setting up the pump; how to clean it
The pump is set up in a guide pipe which is at least one measure larger than the pump. This guide
pipe allows easy removal of the pump for subsequent repairs or maintenance. A stopper is placed at
the bottom of the guide pipe cemented on at the lowest point in the cistern. At the top, it is covered
by almost one metre of earth and it is tied to a support stick.
Water from pumping gets into the guide pipe, at the cistern ground level, at the point where the
stopper is, through a hole perforated with a knife. If for any reason sediment appears at the bottom,
for instance in a flocculation cistern with this system it is easy to remove it. Simply take the pump
from the case and place it down to the bottom through the pipe at the centre of the cement cover.
Then pump, sucking the sediments from the bottom, changing the position of the pump above the
floor. It is a similar technique that is used to clean swimming pools.
Building a Horizontal cistern
This cistern design is used in rocky soils where deep excavation is not possible. The horizontal cistern
is more complicated than the vertical cistern, because it requires a vault as part of its cover.
Flat tiles could be used to cover the cistern but the EMAS technique is cheaper and simpler. With
this technique no iron bars are used because the structure is self supporting.
The first part of construction is to excavate a hole in the shape of a ditch. As a rough guide we
suggest 3 metres long and 1 metre wide. Depth may vary from 1 to 2.5 metres. When digging it is
46
important to leave an inclination the bottom of the ditch, to the side. Subsequently, the pump and
the cover will occupy this space.
To set up the vault, start as shown in Figure 2. The edge around the hole must have approximately
20 cm depth and about 30 cm width. Then set up 5 sticks as thick as a fist. On these sticks, set up
thin branches, stalks, etc. It is important to cover only the area of the hole, and not the lateral
deepening. Next arrange plastic or cement bags on the branches, and spread earth on them. This
earth is used to form the vault mould. The curve is similar to the segment of a circle in which height
is equal to the fourth part of its width. On the earth mold, arrange papers or plastic, and on them,
the cement mortar which is in the proportion : 3. To increase the thickness of cement, add some
stones and mix them with the cement mortar. Then cover the cement and let it harden.
When 5 days have elapsed, the transversal sticks may be cut out, starting with the inner ones. Then
the sticks are dropped with the earth mould earth, and only the vault remains. The next steps are
quite similar to those for the vertical cistern.
47
48
Surface cistern
Where it is not possible to dig, an EMAS design surface cistern may
be used. This is actually a classic ferro-cement tank, the differences
being that it is more compact, and has no foundation and therefore is
more resistant to fissures. Its construction is simple and inexpensive,
as it does not require much material or wood :
Materials: Iron bars : All iron bars are 1/4". Ten rings, 1.87 metres
diameter (6 metre round shaped rods with 10 cm overlap make a
1.87 metre ring). For the base and the vault, use two 1.40 m rings,
two 90 cm rings and two 60 cm rings; you also need 60 metres of
chicken wire, 2 Kg of lashing wire, 400 Kg of cement and 600 Kg of
fine sand.
Construction : To obtain the self supporting base, build on the ground
a round, shaped small hillock made of earth, the same as for an EMAS
cover. Its diameter is 1.80 metres; its height : 45 cm. On this mould,
arrange a plastic sheet; then set up a cage with the iron tools,
starting with a ring at the base. Initially only 4 supporting beams are
set up, on which the lateral rings are arranged, from 15 to 20 cm
between them.
To strengthen the supporting beams, provisional sticks are
embedded, about 2 metres high. Then the remaining 26 supporting
beams are arranged, 20 cm between each. All iron crossing joints
must be tightly tied. Once this cage wall is finished, an iron wire is
made for the floor and the roof, using the smallest rings. Then
cement is cast for the floor with a 3 : 1 mortar.To facilitate getting
into and out of the tank while works are being carried out it is of help
to build the framework of a ladder. This will also serve the purpose of
a roof for shade, and as protection from rainfall.
Once the cage, the cement floor and entrance framework with its
Roof is finished, set 4 screen wire arrangements on the cage. It is
easier to use rolls of 50 cm width, since they can be better applied .
Tie the mesh to the iron bars. Its only function is to hold the cement
from the mud cake, as for this kind of tank no plank lining is used.
Start from the bottom, spreading the 3 : 1 cement on the mesh.
The person who is inside must hold a board against the mesh, to
prevent cement from dropping. When the wall is finished, cement
must be allowed to harden for one night before starting to build the
roof. For this purpose, simply spread half dry mortar on the mesh,
and arrange supporting beams inside it. The round shaped intake
hole, of about 60 cm diameter, is in the middle part. When the first external coat is finished, start
the inner mud cake, and finish the coat on both sides. The wall thickness should be about 5 cm.
49
Finally spread whitewash inside and outside. The intake hole may be covered with an EMAS concave
cover, but as no free space is left between the gutter and the tank to set up a filter, you can
incorporate the filter into the same cement cover (please see the diagram). Outlet connections can
be arranged as the case may be. When using an EMAS pump, they can be set up next to the cover.
Semi embedded cistern
Sometimes an excavation is carried out for a deep cistern, and at three metres depth you find that a
solid rock is obstructing it. The water volume available for storeage, would not be sufficient due to
the shallow depth. In this case the excavation can be enlarged by a width of up to 2 metres by raising
a large and tightly compact earthen wall thus increasing the effective cistern depth of the cistern.
The thickness of the wall depends on the height you wish to reach, and it must be at least 70cm at its
bottom if its height reaches 1 metre. For this system we do not recommend exceeding one metre in
height.
The normal cover would be too heavy to cover this 2 metres wide cistern. In order to reduce its
diameter, build a vault in the normal way, but leave a round shaped intake hole in the middle, of
about 60 cm. Then cover this intake hole with a cement cover, as shown.
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FAILED EXCAVATED WELL TRANSFORMED INTO A CISTERN This design is useful if no water is found when excavating a well.
Instead of work being lost in a useless hole, it can be easily
transformed into a cistern with a high water volume. The steps to
be taken for its construction are the same ones as described in
the preceding pages. The situation is more complicated when the
well has already been jacketed. You must check that the jackets
are pressure resistant, or that they are tightly attached to the
firm earth of the wall. Otherwise, cracks will appear and water
will be lost (if there are any cracks, use water with clay to obtain
an adequate filling). If cracks have formed, due to pressure
pushing the jackets towards the firm earth at the wall, it becomes
necessary to spread a new mud cake coat inside. Then the cistern
will be made waterproof.
If no appropriate roof is available nearby, a temporary watershed
can be used, or the water from an occasional ravine. To obtain
crystalline water from a ravine, treatment with a flocculation and
sedimentation tank is necessary.
Advice to make it waterproof
Sometimes very small pores remain, or small fissures are formed
at the cistern wall, allowing water to leak and this is another
problem with stagnant water. The easiest - and also the most
inexpensive - way to do it, is to paint the wall with asphalt paint.
This paint is prepared by melting asphalt stones and mixing the liquid with gasoline. You should be
very cautious when mixing hot asphalt with gasoline, since the steam formed is highly explosive.
Therefore this must be carried out only in the open air. You can also purchase this paint at local
stores, already prepared. It is in the maintenance of asphalt paving, or in car metal plate work. The
more dilute the paint the quicker it will dry so a concentrated paint may take too long to dry. Instead
of asphalt paint you can use diluted paraffin or swimming pool paint. When painting the inner side
of a cistern, there is a great danger of asphyxia, due to poisonous gases that evaporate from the
paint. To get fresh air into closed cisterns, breathe through a hose with its other end exposed to the
air outside. You must always use a good ladder, and someone should stay nearby, to assist in case of
emergency.
Disinfecting with chlorine
Disinfecting with chlorine (lye, bleach, etc.) guarantees healthy water, free of microbes. A 0.8
milligram concentration per litre gives a long disinfection time.
The following is a guide for chlorination. The value is multiplied according to the volume of the
cistern. A spoonful has approximately 5 cubic centimetres. If the measures indicated are changed
slightly, this will have no great affect. Another practical method is to pour chlorine until the flavour is
similar to water from a big city.
51
If using 5% sodium hypochlorite, pour 16 ml for each cubic metre of its volume. For instance, for a
5000 litre cistern, use 80 ml. When using 10% sodium hypochlorite, pour 8 ml for each cubic metre
and pour this into a 5000 litre 40 ml cistern. Final remarks : These types of underground cisterns
have been designed for dry places, with compacted earth. Vertical cisterns have also proved to be
excellent in very sandy soils. No underground cistern is recommended for very humid soils or in soils
with recent refills, due to the risk of landslide. The horizontal cistern is not recommended where
frost penetrates more than 40 cm. Also no tall trees should exist nearby, as tree roots may damage
the cistern. The vertical cistern (the deep cistern) has many advantages over the other types because
with deep sites, roots are less harmful, the earth is firmer, no frost penetrates and there is less
danger of surface infiltration. To store good quality potable water in a cistern, it is always
recommended to chlorinate it .
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SUPPLEMENTARY CISTERN
A supplementary Cistern is useful in the following cases:
1 . where the water source is delivered via a pipe but where flow is irregular;
2 . where the well dries up in a determined season
3 . where insufficient roof area exists to provide a good supply
1. When water flow is received irregularly
and intermittently, and if the user is not
present the flow is lost and scarcity results.
In this case the solution is to prepare a tank with
a float valve. When there is water, the tank is
filled and when it is full, the float valve
automatically shuts. If water has a good
pressure, it is convenient to build the tank above
the highest faucet of the dwelling (shower or tap
on the second floor). But frequently the flow
received is minimal and an elevated tank cannot
be filled. The disadvantage of using tanks and
other containers is that water is polluted, and
this risk is increased when small containers are
introduced. The solution proposed by EMAS for
this case is a ferro-cement underground cistern,
and a FLEXI pump.
To regulate intake and prevent overflow,
arrange a float valve. As in small impoundments
from watersheds, a polyethylene oilcloth is
arranged between the vault and the surface, so
there is no infiltration of water spilled from the
pump. When electricity is available, you can use a
small 200 Watt centrifugal pump.
2 . If the excavated well dries up
Some wells have enough water most of the year,
but they dry up during the low water season. It
may become expensive to get some water during
those months, most of all when no other source is
available nearby.
53
If the deepening had no positive result (excavating or drilling a root) the possibility exists to build a
cistern near the well. It can be filled when the well receives a water inflow, and be kept as storage
when the well dries up. In the cistern, you can also add water from a roof nearby. The FLEXI pump
makes it possible to pump directly from the excavated well to the cistern.
3. What to do when no roof or well are available
In this case, a cofferdam is built, enclosing a ravine or a rain water flow. This system is most feasible
in mountainous areas.
When it rains, water runs by the ravine and it is stopped at the ravine. Sand and earth settle down.
The lagoon is only temporary, and in a few days water is lost to the subsoil, or else it evaporates.
Therefore, water must be conveyed to a cistern through piping; there it will be stored until it is used.
The filter is most important before inflow to the cistern. If earth or organic matter get into the
cistern, they will rot, forming sulfur combinations with unpleasant odours.
Using a filter of polyester fibre (EMAS filter) or a slow sand filter (it needs much more space) almost
all organic matter is eliminated and if some turbidity still exists, it settles in the cistern, causing no
fermentation.
Finally, do not forget to chlorinate water. For the above cases we recommend a high concentration,
1 milligram per litre ( for a 9.000 litre cistern, a small bag of chlorine or bleach).
54
COMBINED IMPOUNDMENT, A DRILLED WELL CONTAINING SALTY WATER, AND
HARVESTED RAINWATER
There are places where water in the subsoil is salty, it has an unpleasant flavour, it contains
excessive amounts of fluorine or heavy metals, or its bacteriological quality is uncertain.
In such cases we offer the combination of a drilled or excavated well, and harvested rainwater.
Generally waters from the subsoil can be used for washing, personal cleanliness or for the privy.
Fresh rain water is exclusively used for cooking and drinking.
The advantage is that the supply has a minor cost, although service is 100% and practically no
limitations exist in water volume. There is no danger to health, as a result of having taken too much
salt or poisonous substances.
This system has had excellent results in the Paraguayan Chaco, where underground waters at all
depths are salty and not potable. Their phreatic level is quite high, about 8 metres. At lower levels,
good aquifers exist and an EMAS manual drilling does not surpass 20 metres, which means an
approximate cost of 60 US$/Euros. The soil is easy to excavate; it is firm and dry, which allows the
cistern to be set up. The cistern volume for a family dwelling is calculated at 3000 - 4000 litres, that
is to say 3 - 4 cement bags. This do it yourself building method, Shows a cost for the whole system of
150 US$/Euro
55
POSSIBILITIES OF USING MOTORIZED PUMPS FOR EMAS WELLS
Single suction
When the static level of an underground water is shallow,
and the well yields a good volume, then the simplest way
to motorize pumping is by arranging a centrifugal pump
next to the well. The suction pipe must be brought down
about 11 - 12 metres. Although the static level is located
only 5 metres deep, when pumping it goes down to its
maximum suction level, that is to say about 8 metres. The
suction pipe must have a check valve at its sharp end, to
prevent water from flowing back to the well when the
pump stops, and thus emptying, given that most
centrifugal pumps cannot suck air.
In standard EMAS wells we use 1" or PVC 1" polyethylene
flexible pipes for suction with a home-made check valve
at the bottom, and a good quality check valve located
before reaching the pump.
A home-made check valve at the well has the advantage
that it goes inside the narrow 1 1/4" jacket of the well,
and at the same time it can be used as a reverse hydraulic
ram to pump water upwards and thus fuel the pump.
The purchased check valve (it does not fit inside the well,
because of its larger diameter) completely blocks water
from flowing back into the well once the system has been
set in operation.
56
USE OF A MOTORIZED PUMP IN AN EMAS WELL WITH A DEEPER STATIC LEVEL (PUMP
BROUGHT DOWN IN A DRY WELL).
In this case the static level is so deep that it does not allow
suction from the surface. The problem may be solved by
bringing down the pumping equipment to a depth that
allows suction.
Usually, beside the EMAS well, a dry well is excavated, with a
diameter of 1 metre or more. The depth of the dry well
determines the static level during the low water season, and
its highest level during the rainy season. Normally the static
level does not rise more than 2 metres in deep wells, and the
pumping equipment can be set up about two metres above
the highest level. But if during the rainy season the static
level in an EMAS well goes up more than 5 metres, this
system is not applicable anymore, because the risk exists
that during the rainy season the dry well will overflow, and
during the low water season the static level goes down to
such a point that the pump is not able to suck the water up.
The walls of the dry well can be stabilized with a cement
layer.
Rain water must also be prevented from getting into the dry
well and damaging the engine. It is advisable to use an
electric engine, but a gasoline operated motor can be used,
after insuring that the exhaust pipe is drawn out to the top.
Where the motorized pumping equipment fails, a FLEXI
pump can be easily set up.
57
A MOTORIZED PUMP IN A WELL EXCAVATED AND DEEPENED WITH THE EMAS SYSTEM Where the EMAS drilling does not provide sufficient water volume, drilling can be combined with an
excavation (Please see well drilled with reservoir).
The situation is similar to when an excavated
well does not provide sufficient water
volume. In this case the excavated well can
be deepened by means of the EMAS drilling
so that a deeper aquifer is reached.
If the suction from the surface is not
sufficient, then this alternative is viable. The
pumping equipment is set up on a pontoon,
which may be built of plastic containers or of
Stiropor. Only an electric engine will suffice.
The pontoon goes up and down with the
pump inside the well. The flexible hose
compensates for the ups and downs. This
system is more useful in wells where the
water level varies considerably between the
low water and rainy seasons. A check valve
must be arranged at the suction pipe, to
prevent water from flowing back into the
well.
The same pumping system is also applicable
in single excavated wells (with no EMAS
drilling).
It is advisable to set up a "float" switch that
automatically switches off the pump engine
when the well is about to be empty. This will
prevent damage to the pump.
Some of the advantages of this combined
well are its higher volume, its large deposit,
and a more effective pumping. In case the
motorized pump fails, a EMAS pump can be
easily set up.
58
PUMPING WITH COMPRESSED AIR An air pump is one of the simplest form of pump that exist. You only need a small compressor with
its engine, whether electric or gasoline, and a thin pipe or hose that must reach down to the bottom
of the well. The advantage is that all the revolving and abrasion parts are located on top, and are
therefore easy to repair and to maintain. The air pump can extract water from a well with a static
level below 20 metres, provided the recovery be good and the well has the appropriate depth. The
relation between energy consumption and water volume is acceptable when dealing with wells of a
reduced diameter.
In the compressed air pump, advantage is taken of two elements of differing density. Air forms with
water a sort of a foam which is much lighter than water, and it can float. Thus, on the water a foam
column is formed, which may even reach the top of the well.
Three factors have an influence on air pumping:
First : The relationship between the dynamic level and the well depth. (The dynamic level is the one
reached by the water level under constant pumping with a determined volume). It is convenient for
this relationship to be at least one to one, that is, one part water and one part air. For instance a 40
metres well has a static level at 10 metres. Constantly pumping 1 litre per second reduces the level
down to 20 metres (dynamic level).
Then the relation in the well is one to one, one part water and one part air. The extraction volume is
poor, because a large quantity of air is required to produce a light foam that it can reach the top.
Also, the yield is low.
If the well has 60 metre depth, that is to say 40 metres of water, then the foam needs less air to go
up and the water – air mixture contains more water; therefore, we get a higher extraction. The
deeper the level of the water is in the drilled well, the more water will the air - water mixture
contain.
Second : The volume of air injected. If air is scarce, then the mixture will not float until it overflows.
Too much air utilizes more energy, without significantly increasing the volume.
Third : The diameter of the well or the diameter of the extraction pipe also determines how much air
is needed. The wider it is, more air will be required. As money is usually only available for a small
engine and compressor, a narrow extraction pipe is advantageous (1 1/4" - 1 1/2" outlet pipe, air
pipe, 1/2" polyethylene hose, 1 HP compressor, 1,5 - 3 HP engine).
More than 50% of EMAS wells are adequate for compressed air pumping.
They have a good recovery, with about 11/s by their synthetic pipe, and they have a favorable air
and water relationship, as a result of their significant depth. Because of their reduced diameter, 1
1/4" - 1 1/2" , they do not require a very powerful compressor or another extraction pipe.
Their installation is quite simple : The engine can be electric or gasoline operated. Drillers use a
gasoline operated engine with only 3 HP and operated with a minimum acceleration. The
compressor is similar to the smallest one used by tyre workmen. An air chamber is not needed; air is
59
ejected directly from the compressor, it passes by a few cooling turns and goes into the oil disposal.
From there, a 1/2" pipe reaches the bottom of the well. Air is ejected from its open side. Water gets
into the tank, in a 'coughing' motion of the water with air. The oil disposal or oil trap is a piece of 1
1/2" galvanized iron pipe and full of wood shavings. The fine smoke from the oil exhaust of the
compressor sticks to these wood shavings. The base of the valve serves to pour out the accumulated
oil. By means of the upper valve you can remove the air pressure from the pipe, and thus obtain a
smooth engine start
60
THE EMAS LATRINE DOES NOT AFFECT AQUIFERS, IT IS COMFORTABLE, HYGIENIC AND
ALMOST ODOURLESS.
If we wish every dwelling to have its own
impounded water resource using underground
waters, we must prevent these resources from
being polluted by infiltration of sewage. A
latrine is accepted when it is easy to set up,
when it is inexpensive, has a nice appearance
and most of all, when it does not have a bad
smell. The EMAS latrine has more advantages
than a water closet with running water
because it is odourless, is very economic, it
does not damage the aquifer because water is
contained, and its content becomes a good
manure. EMAS latrines are offered in two
designs : the High Set Up Latrine and the
Portable Latrine.
As you can observe from the design, this is a
booth built with metallic plate and with a ferro-
cement tiles as a platform, and another one as
a roof. The door is made of wooden frames or
15 mm x 15 mm industrial pipe and lined with
corrugated tin plate. A chimney painted in
black extracts air.
How to build the EMAS latrine, step by step.
The booth . This can be built semi round, round or oval shaped. It needs no woodwork, since the
corrugated tin plate or the trapezoidal plate is self supporting. The laths for the door and its frame
are not difficult to find. If a number booths need to be transported, there is no problem because the
material is not bulky and it has not much weight.
1st step : material for the walls: You need 4 corrugated tin plate sheets Nº 33, or even better Nº 28,
or three trapezoidal plate sheets, from 1.80 to 2 metres length, 12 metre wooden laths or 15 mm x
15 mm profile pipe, aluminium rivets, 2 hinges, 2 knobs and 2 latch keys.
2nd
step : the wall and the door: The door with the laths is set up on site. The 4 corrugated tin
plates are joined with rivets as per their width, to obtain a plate at least 2.40 metres wide. Then you
nail both sides to the door frame, giving it a semi round shape at its bottom.
3rd step : the floor and the roof: A ferro-cement tile is cast which serves as the base, with a hole left
for the seat. It is better to build it of ferro-cement, because this is lighter and more economic. The
sizing of the base is dependent on the shape of the booth. The thickness at the bottom should be
61
about 4.5 cm; at its four "corners" it has 4 rings or hooks. The roof tile is about 4 cm thick. Iron bars,
of 1/8" are also used.
4th
step : the choked up well: EMAS does not recommend the hole to be too deep, as too deep a hole
can affect the aquifer, be easily filled with water, or it may collapse and endanger the booth and the
person inside it. A diameter of 60 cm - 80 cm diameter and a depth of 1 metre to 1.20 metres will
suffice for one family. A hole, for a dry latrine, with a depth of more than 2 metres has no
advantage. Rather it has the diasadvantages mentioned above.
5th
step : setting up the booth 'in situ': When the hole has been excavated, and using the earth left
over for an embankment, carefully arrange the tile for the hole, insuring it is on the same level. Then
set the plate booth on the tile and arrange the oval shape. To fasten the plate on the tile, place a
mortar on both sides around the plate.
6th
step : the roof: Like the floor tile, a thin ferro-cement tile is used for the roof. The tile should to be
thin, but reinforced with 1/4 iron bars. Like the floor, its edge has a hard mortar lining between the
tile and the corrugated tin plate.
7th step : Ventilation system: This latrine has two kinds of ventilation. One of them to maintain the
environment inside the booth free of odour, allowing air to circulate through the windows/gaps at
the door, and the other is remove odours coming from the septic well.
The ventilation of the well eliminates odours in the booth, as a result of the air intake at the seat and
air outlet by the chimney.
This movement of air removes the bad odours from the cavity. For air to circulate up the chimney,
there must be a difference in atmospheric conditions. During day light, solar rays warm up the
chimney (They also warm it up when the sky is cloudy) and during the night, when the air is fresh
outside, it is lukewarm in the well, and it tends to go upward. The chimney must be painted black, to
absorb solar rays. The revolving pipe, which due to its tail is always opposite the sun, promotes
additional suction in the chimney, and increases air extraction.
62
63
HOW TO BUILD A LAUNDRY TILE In rural areas it is frequently
difficult and expensive to obtain
a laundry tile. High transport
costs, the risk of it being stolen,
and the high price of the tile
itself make people give up on
this useful domestic tool.
The person who knows how to build his tile on site can help the community, as the most important
part of the material, sand, is frequently found in rural areas. Finding half a cement bag and some
iron bars, the other materials, is not so difficult.
Its construction :
A fine sand mold is cast, or
simply an earthen mold, the
inverse shape to the tile to be
constructed.
To mold the earth/sand,
moisten it a little. If the sand
is somewhat thick and cannot be easily mixed, then mix it with sifted earth to form moistened mud.
When molding, we recommend people to be careful and see that water always slopes to the
bottom, where the drainage is located. To achieve this the tile must have an inclination from its
lateral areas towards the middle part. The same thing is applicable to the bottom of the tile: the
drainage hole must be at its lowest part, and so that when setting the mold inversely, it should be on
its upper part. The mold must be polished as much as possible.
Then prepare a solid cement mortar, 3 : 1, and spread it
from the edges to the inside part. This first layer must end
at its upper part. The thickness of this first layer should be
about 2.5 cm. Use a 1/4" or 6 mm iron bar. Please see the
schedule for iron bars'. On this first layer, another cement
layer is spread, again of about 2.5 cm. At its upper part,
insert a 1 – 1 1/2" pipe which will serve subsequently as
drainage.
After 2 days the tile stand is
ready. To avoid breaking the
mold, hold it at one of its narrow
sides when picking it up. Scrape
the sand, then wash it with a
brush or paint brush, and finally
polish inside with sifted sand and cement. To polish, use a piece of sponge as a tool. For the cement
to continue being moistened while it hardens, arrange wet sawdust on it.
64
HOW TO BUILD A SEAT FOR A LATRINE The construction of the EMAS latrine has
been described in the module on water
hygiene. Here we describe how to build
the seat for this latrine. For a latrine to be
accepted by the community/individual, it
is important that its seat be comfortable
and hygienic. A plastic cover and a plastic
seat are indispensable for hygiene and
comfort, therefore they should not be
overlooked.
Building a seat for a latrine is quite similar
to building a laundry tile. A mold is made
of earth/sand, then it is made resistant
with cement mortar. At its upper part,
the earth/sand mold must have the same
diameter as the seat inside it. It is easier
to spread a layer with mortar on all the
mold, including the upper part.
To arrange the seat, perforate the edge
of the seat itself (a simpler matter) or
make the holes at the projected points
where the seat wheel rings are arranged.
With pieces of wood or earth, a support
is cut according to the size of the seat
wheel. We recommend the diameter of
the seat to be slightly larger than the seat
wheel, most of all at its front part. The
seat does not require iron reinforcement,
because the form it has gives enough
stability to it. After 12 hours have
elapsed, the final coating is laid at its
external part, and 48 hours later sand can
be scraped and the seat is finished.
65
EMAS MICRO IRRIGATION SYSTEM The EMAS system can be used for several different types of irrigation. The most common one is by
gravity to the furrows/planted area. This involves filling the tank with water, whether it is a 'pitcher'
or several big ferro-cement containers, and through piping, water is conveyed to the furrows. The
great advantage of drip irrigation is that water is used more efficiently as evaporation from the soil is
at a minimum, and there are no losses to deeper areas due to infiltration
.
Therefore, with the same volume, up to four times more plants can be irrigated. For years EMAS has
developed a very interesting drip micro irrigation system, which is ideal for a family vegetable
garden, or to cultivate small coffee plantations.
Many of the components of such systems are presented above and these include the EMAS FLEXI
pump, the ferro-cement tank and the filters. It is not difficult to distribute water to furrows through
a pipe system, due to the fact that this manual explains accessories such as T's, bends and plugs. In a
drip irrigation system all water must be equally distributed. Drip pipes must not be obstructed but
where they do repair should be easy.
Generally this type of equipment is supplied by commercial companies because the design of the
pipe work is specialized, as the inner working of the drip feed pipes has to ensure that only drops are
ejected. In some home-made systems, holding screws are used to regulate drip feeding, but they
66
tend to become loose easily and are very susceptible to being blocked, whether by small dirt
particles or because rust has formed. EMAS had the idea of perforating a pipe and passing a string
through the hole, this string being a piece of polyester synthetic cloth or perlon (also old nylon
stockings would do). This string/strip is tightly tied to the pipe. Water is forced into the space where
the fibers are, and passes through the perforated hole, by capillary action and then drops outwards.
When the water includes small dirt particles , these dirt particles remain attached to the strip/string
inside the pipe, like a filter. Dripping is reduced only when all the strip inside the pipe is blocked with
dirt. To reactivate dripping and clean the strips, the strips are moved pulling them on one side and
then on the opposite side several times, until no more dirt is left. To reduce maintenance of the
system it is important that clean water is used, without with any dirt particles. If crystalline water
from a well is used, there will be no problem. But if you are using water from a river or from a
lagoon, then a filter must be arranged. See the EMAS filter.
Drip irrigation is set up according to the crop being cultivated. When sowing vegetables, a drip
aperture every 50 cm will suffice, that is to say, from 2 to 4 dripping apertures for one square metre.
Usually in drip irrigation, only some small areas are wetted and not all the land being cultivated.
Capillary attraction ensures that the water is distributed in the subsoil. To reduce water evaporation
even more at the surface of the earth, it must be scraped on top, similar to removing weeds, and the
loose earth will "balance" and thus interrupt the capillary channels which would otherwise transport
humidity to the surface.
Industrial agricultural undertakings take advantage of drip irrigation when applying chemical
fertilizers to plants. In the EMAS design, some chemical fertilizer is dissolved, and this scented water
is applied from the ferro-cement tank. Thus the fertilizer reaches the plants together with water.
Pedal adapted EMAS pumps for irrigation
There are several different types of pedal
operated pumps, that can be used in
irrigation. Pedal powered pumps have the
advantage of being less tiring than the
manual form, as the muscular structure of
the legs is stronger than that of the arms.
Pedal pumping is similar to a children's
seesaw. EMAS pumps have the advantage of
conveying water from a long distance or to
elevate it to a height of up to 40 metres.
Pumps can be built based on flow or height,
By merely varying the diameter of the
cylinder. The EMAS pedal system always has
two twin pumps operated by a lever with
equal arms. When one side goes up, the
other side goes down. When going up, the cylinder is filled with water and at the same time the
other cylinder is emptied, because its piston goes down. There are three different types.
67
1 . lake or river pumping
For this type of pumping, a
compact portable mechanism is
used. The valves are made of
galvanized pipes and the
accessories, are very similar to the
ones used in the mud pump for
drilling wells. Both valves are
located at the same level, at the
lower part of the pump, and they
form the valve head. On its upper
part it has a 1 inch screw thread, to
which the reduction coupling is
threaded for the plastic cylinder
pipe. The advantage of a PVC
cylinder is that it is more polished,
and therefore it has much less
friction than a steel pipe. The
diameter of the cylinder may vary,
according to the pressure needed.
Usually diameters from 1.5 to 2 inches are used for irrigation. The cylinder is a pipe of about 40 cm
with a screw thread on both sides. A reduction coupling connects it with the head.
On its upper part it has another reduction coupling which operates as a guide for the connecting
rod. The piston is simply a piece of galvanized pipe, plugged on its lower side. If accurate, it needs no
gasket, otherwise it can carry a gasket made of tyre or cloth. The connecting rod has two hinges,
that allow compensation for the motion, fastened on the pedal board. All the framework is welded
and made of 1/2 inch iron for construction.
68
2 . pumping by twin drilled wells
If the subsoil has a good quality aquifer and if the land can be drilled, you can choose the twin wells'
system. With the EMAS system, you firstly drill two wells, 80 cm distant. Then set up the EMAS
pumps in the wells. When using 2" jackets, flow pumps can be used, but if water is found at more
than 10 metres depth, or if the recharge is not good, it is advisable to use 1" standard pumps.
The remaining part of the mechanism is quite simple. The seesaw is installed, putting the connecting
rod, at both ends, with its two hinges. The fastening between the connecting rod and the holder is
made by welding a 3/4" pipe which has been cut lengthwise and operates as a gearing, to which the
holder is tied with a pneumatic tyre strip (see diagram).
3 . pumping of an excavated well
The system is quite similar to
that of a twin well. Set up
two pumps, laterally, 80 cm
distant. Given the inclination
of the lateral pumps, the
shaft of the "seesaw" must
have the same angle.
However, this means that
the balance board will also
have an inclination, making it
most unstable to step on it.
Therefore, to level up the
stepping board, place two
platforms to operate as
wedges on the board.
69
SMALL FERRO-CEMENT TANK OR 'PITCHER'
This type of container is very economic, it has a long life span
and it can be built almost everywhere and of any size. In Bolivia,
the price of a self constructed tank, with a volume of 200 litres, is
of about 10 Euro/US$.
Construction steps:
Set up screen wire on an iron ring. The longer overhanging wires
will subsequently serve to reinforce the wall. Spread a film of
cement mortar on the screen.
When the cement at the bottom is half dried, arrange a bag on it
of equal size to the proposed tank. Fill this bag with earth, sand or
sawdust.
Then spread the first coat of the mortar on the bag, 1:3.
Raise the lateral wires, hooking them to a small ring which will reinforce the mouth of the tank, and
is horizontally enveloped with lashing wire. Set a second mortar layer on the wires.
When the neck is finished, arrange the connecting nipples.
70
After about 20 hours, the bag is emptied and the tank is finished. After putting a cement whitewash
layer both inside and out, the tank must be kept moistened for about 5 days, so that the cement will
harden.
Some uses :
As a triple septic chamber;
As a domestic water reservoir ;
In the EMAS sanitary module;
As an underground tank in a micro impounding.
71
BUILDING PVC ACCESSORIES
Hard soldering with a special adhesive.
We use this kind of soldering to join the pipe bells. The adhesive consists of a diluting liquid diluted
with a PVC material.
When the diluting liquid is applied it attacks the pipe, dilutes part of the pipes surface resulting in
both materials being mixed, i.e. the pipe and the adhesive. When the diluting liquid evaporates, the
PVC from the pipe and the liquid have fully mixed and act as the adhesive. It is most important,
when soldering, to have the pipe surface clean, so that the diluting liquid may attack the pipe and
form the joint.
Hot air soldering
This system is very practical and it has multiple uses. It operates like a hair dryer. Hot air Is used to
soften the pipe material, and the soldering solution is added with a small soldering bar made of the
same material as the pipe. When the pipe and soldering become malleable under the effect of heat,
a firm joint is formed.
Plate soldering
This very practical method is used frequently by EMAS as it can be used almost everywhere and with
no special tools. Using this method all forms of strength resistant materials, T bends, V bends and
siphons, used in pressure systems and sewerage systems, can be soldered.
The method is as follows:
Exercise: Making a 1/2" bend
The first step is to cut two pieces of about 4 cm length from the pipe bar. They must not be cut
straight, but at a 45º angle. To obtain the exact angle, we use a square. (Fig. 1 ).
After the pipe is cut, the cutting edges must be polished and the angle checked for accuracy against
the square.
Both pieces are polished until they can form a 90º bend ( Fig. 4 ). Then, with a knife, clean the
shavings attached to both sharp ends.
72
A flat plate is required for soldering. The flat bottom of a frying pan, or the base of an old electric
iron will serve adequately.
The plate is set up over a heat source.
Before soldering, the appropriate temperature must be reached, and this can be checked by using
another piece of pipe and slowly scratching on the hot plate. If the plastic holds, like a chalk stripe, it
is hot enough. If the white color of the PVC quickly turns yellow and then black, it is too hot. The
temperature is adequate when the color slowly turns yellow (within about 15 seconds) and there is
no smoke.
When the correct temperature has been reached, press the two pieces on the plate and move
them slowly to be sure that both surfaces are being equally softened. Before picking up the pieces
from the plate, stop pressing for about 3 seconds, so that a flexible material is formed, which will
subsequently serve for soldering. Then pick them up quickly and join them without delay (Fig 4).
As a guide to finding the correct position, quickly and easily, It is helpful to use the index fingers (Fig.
4) The bend is now practically finished. If you need a bend with bells, you must introduce a pipe of
the same diameter to the heated bell of the pipe. When the pipes are attached the bend is cooled
quickly in cold water (See Figs 5 + 6 ).
Building a 1/2" pressure resistant T
The T consists of two halves of a bend. We first cut two bends as described above. The difference is
that one arm of each bend is short (approximately 5 mm) and the other arm is normal sized (Please
see Figs 1,3, 3). Solder as above to obtain two bends. The next step is to cut each bend at a point
slightly less than half the bend(Fig 5 ) and then join the two bends once more, thus obtaining a T (Fig
73
5ª). After soldering, remove the excess and ensure that all pipes are aligned and polish by filing
grinding or scraping on a sharp surface. The last step is to solder a nipple of about 3 cm on the fork
so as to obtain a well rounded outlet in order to make the bell or screw thread. If you wish it to have
an external screw thread, use a threaded nipple (Please see figs. 5 a, 6).
To build T's and Y's for drain pipes, another technique is used. In this case soldering is not
performed on a plate, rather, the fork is arranged and soldered with adhesive.
Building a 1/2" drain pipe (sanitary) T.
This technique can be used for/with pipes of all diameters and resistance. When using PVC pipes
with a calcium carbonate (ground lime) content, the pipe loses some of its
plasticity and the result obtained may not be very satisfactory.
A 16 cm piece is cut from the pipe. This piece will be the central part or
body of the T. A 5 cm pipe will form the fork, and a 2 cm pipe will be the
"core barrel" (Fig 1 ).
Take the central body and the core barrel and set the core barrel on the
middle part of the body. With a pencil, mark the round shaped edge of
the core barrel on the central body (Please see Fig 2 ). Theoretically this
mark represents the hole of the forking.
However a rise is required to stick the fork on the body of the T.
Therefore when cutting the gap, allowance should be made for the
material required for this peak. To facilitate this another mark is made,
elliptical in shape, on both sides ca. 0. 6 cm.
Then take a sharp knife and with a gas flame or a candle flame, heat the
sharp end of the knife as well as the marked part of the pipe (Fig 3).
When the hot knife has softened the marked part of the body, you can
easily cut the marked part of the pipe, like a piece of cheese.
Once the marked part has been cut, prepare to draw out the core barrel.
Heat the marked part again (only the marked part) and test its flexibility
74
by quickly touching the plastic with your fingers (Fig 5).
Then introduce, sideways, the core
barrel ring into the body, with its
aperture/centre towards the hole.
Arrange it at the middle part;
introduce two fingers on both
sides, and push the core barrel
upwards. When the core barrel
goes upwards, it will also raise the
edge of the reserved material
upwards, and thus it will form a
peak. The core barrel is left in its
place while it is cooled down with
water.
Finally draw aside the core barrel and introduce the forking pipe into the hole. To prevent the
forking from being obstructed, press it into a semi round shape at its bottom (See Fig 6 ). Then
spread PVC adhesive, and build the bells where they are needed.
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WINDMILL WITH THE EMAS PUMP
The EMAS pump can be easily adapted to
windmills. These mills are easy to construct, no
gear system is necessary for pumping, and it
produces a higher yield and costs less. It is
adaptable so that if you wish to convey water a
certain distance or height, a pump with a thin
cylinder is used, and if a greater volume is
required, a wider cylinder is used. The pump can
be adapted to different revolutions of the mill, by
adjusting the length of the crankshaft. In windy
areas , or where the mills have few blades, the
number of revolutions are increased, and
therefore the length of the crankshaft should be
shorter. In calm areas with larger mills with many
blades revolutions are slower, and therefore the
length of the crankshaft can be increased.
In order to prevent wind overcharge and damage
to the mill, most mills have an automatic safety
latch. This safety latch consists of the following
the revolving shaft of the sprinkling nozzle is
located about 10 - 30 cm horizontally distant
from the vertical shaft. Its tail end is fastened to
the body of the sprinkling nozzle by a spring. The
tail end is always oriented towards the wind, and
it is located precisely behind the vertical shaft.
When the wind speed increases to a certain limit,
then the wind pressure on the blades of the
sprinkling nozzle is increased, and the spring
resistance is overcome. The sprinkling nozzle of the mill bends sidewise, separating itself from the
wind and reducing speed. If the wind is even stronger, the sprinkling nozzle completely bends
towards the wind, and an immobilization hook is hooked.
EMAS uses a windmill design which costs 300 US$/Euros. It is useful for pumping potable water and
for irrigation. The disadvantage of all windmills is that users generally do not carry out the
maintenance required . A windmill needs to be lubricated now and then, and whenever a piece is
damaged, it must be replaced immediately. Otherwise it can be damaged quickly, and the
investment lost.
It is therefore advisable to promote windmills with caution perhaps only when adequate
maintenance is guaranteed. Otherwise, the choice of a manual pump is more useful.
76
EMAS DESIGN SOLAR HEATER WITH NO TANK
This design has been developed by EMAS specially for the Altiplano, where during winter nights frost
is intense, and a beaming sun predominates during the day.
It is very expensive to protect water heaters from freezing, because special insulators are needed, as
well as double and even triple glazing. Another method would be to fill the water heater with anti
freeze liquid and use a separate circuit.
This water heater needs no special protection from frost, because it is formed by wide piping which
store such a large water volume that it is never fully frozen, not even during the coldest night.
The following day, when the sun rises again, ice is quickly melted (if there was any) and the water is
heated. At about 10:00 a.m. you already have lukewarm water, and by noon it is burning hot. If this
water heater is not connected to a tank, water cools down during the night. This can be prevented
by having a separate deposit of hot water. It is easy to set up. You need 2" PVC sanitation pipes,
discarded bottles, bends, T's, and 1/2" screw thread nipples, pieces of PVC hose, lashing wire, paint
and aluminium paper.
Also, a wooden box, and glass to cover it. The key to this water heater is the use of common PVC
pipes. Glass bottles serve very well as reducers, because heat does not deform them.
Besides, glass is a corrosion resistant material. To remove the bottom of the bottle, set it for about
15 seconds in a pot with approximately 1/2 cm of heated oil.
Then rub with a moistened cloth the place where glass has been heated, and the bottom will crack
instantly.
Next heat the sharp end of the 2" drain pipe to build a super wide bell. Widen the pipe with the
same bottle, using its neck as a ringer. Fitting the bottle inside the bell, the pipe should be slightly
overheated so it contracts and presses the bottle. To prevent the pipe bell from being softened by
the burning sun, resulting in leakage, tightly press them with several turns of acrylic thread Nº 40 or
Nº 60.
Then set up the two distributors with the T's and the hexagonal nipples, and a bend at the end. In
the middle of the T, screw a single thread nipple.
77
As a coupling between the distributors and the bottle, a
piece of hose is used. First you have to heat it, in order to
widen it, and then you must push it over the neck of the
bottle. Once all the bottles have been connected, fasten with
lashing wire, and paint all of it black. To prevent the hose
couplings from burning, cover them with aluminium foil.
Measure the pipe arrangement and size the wooden box
accordingly, and place the glass on top. Like all other water
heaters, this model must be sloped. The hot water inlet is at
the upper part, by the wire screen bar, and the cold water
intake is at its bottom. This system has been designed for a
max. pressure of 1 metre water column, which means that is
must be set up as indicated in the corresponding Figure.
Two methods which can be used to change a drum into a tank for hot water in a water heater
A 30 - 80 litres polyethylene drum can be used as a tank.
1st
Method : The polyethylene switches are soldered in such a manner as to reinforce them, by plate
soldering (see above). Reinforcing is effected by using two nipples instead of one polyethylene pipe
nipple, placing one into the other. One nipple is 1/2" and the other is 3/4". Thus you obtain a better
contact for the solder made between the switches and the drum. The other method , which is the
best one, is to arrange an edge around the hole, where a polyethylene nipple is inserted under
pressure. With a 2 mm bit , perforate a hole in the tank, at the place where you wish the switch to
be set. Then sharpen a stick, of about 10 cm length. The stick must be slightly thinner than the
switch pipe of 1/2". This piece is attached to another stick or a metallic bar, to form an L.
The next step is to heat the drum with a
candle flame, around the small hole,
until it softens a little. Take the stick,
introduce it into the drum and from its
inside part, push its sharp end outwards.
You will thus widen the small hole to the
size of the stick, and at the same time an
edge will be formed outwards. Then let
the plastic cool down, remove the stick
and with pressure, insert the switch
pipe. To increase the resistance you can
tie this edge with Nº 40 or Nº 60 acrylic
thread. When open barrels are used
instead of drums, it is easier to draw the
edge.
The polyethylene drum is corrosion resistant, and it is also resistant to hot water temperature. The
water heater system is the same as already explained.