gray water manual, los angeles california

8/9/2019 Gray water Manual, Los Angeles California

1/45

Pete Wilson

Governor

State of California

Graywater

Guide

Using Graywater in Your Home Landscape

January 1995David N. Kenn edy

Director

Departm ent of Water Resources

Douglas P. Wheeler

Secretary for Resources

The Resources Agency


2/45


3/45

January 1995Pete Wilson

Governor

State of California

Douglas P. Wheeler

Secretary for Resources

The Resources Agency

David N. Kenn edy

Director

Departmen t of Water Resour ces

STATE

OFCALIFOR

NIA

DEPAR

TMEN

TOF WATER

RESOUR

Graywater

Guide

Using Graywater in Your Home Landscape


4/45

Graywater is u ntr eated hou sehold waste water wh ichh as n ot com e in to con tact with toilet waste.

Includes: u sed water from bath tubs ,showers , ba throom wash bas ins , an dwater from clothes was h in g ma chinesand lau ndr y tubs .

Does not include: waste water fromkitchen s in ks , dish wash ers , or lau n drywater from soiled d iap ers.

(from Californ ia Graywater Sta n da rds )

Thanks to the Urban Water Research Association of Australia for their contributionof four illus trat ions from their pu blication, Domestic Greyw ater Reus e: Oversea sPractice a nd its Applicability to Aus tralia.


5/45

ForewordCalifornia's Graywater Standards are now part of the State Plumbing Code, making

it legal to use graywater everywhere in California. These standards were developed and

adopted in response to Assembly Bill 3518, the Graywater Systems for Single Family

Residences Act of 1992.

This Guide was prepared to help homeowners and landscape and plumbing contrac-

tors understand the Graywater Standards and to help them design, install and maintain

graywater systems.

Carlos Madrid

Chief, Division of Local Assistance


6/45


7/45

Table Of ContentsForeword. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . .

Organization. . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . .

I. Why Use Graywater?. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . .

II. The Seven Steps. . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . 1. In vestigate th e Perm it Process......... . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. 2. Prepa re th e Plan ......... . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . .

Estim ate th e Am ount of Gray w ater Your Fam ily Will Prod uce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Estimate the Am ount of Land scap e You Can Irrigate . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . .

Gathe r S oil an d Ground Water Data . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . .

Draw a Plot Plan . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . .

Determ ine the S ize of the Irrigated Area . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . .

Determine the Location of the Gray w ater Sy stem . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . .

3. Design th e Gr aywater System .......... . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . .Plum bing Sy stem : Pipes a nd Valves . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . .

Surge Tank. . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . .

Filter. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . .

Pump . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. .

Irrigation System . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . .

Su bs urface Drip Irrigation Sy s tem . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . .

Mini-Leachfield S y s tem . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . .

. 4. Su bm it th e Plan for Review a n d Appr oval........ . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . .

5. In sta ll th e System .......... . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . ..Purchas e the Equipm ent. . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . .

Install the Plumbing System . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . .

Ins tall the Su bs urface Drip Irrigation S y s tem . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .

Ins tall the Mini-Leachfield Sy s tem . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . ..

6. System In sp ection an d Appr oval........ . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . .

7. Using, Monitoring an d Mainta ining the S ystem .......... . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .Protect H ea lth. . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . .

Select Garden-Friendly Soaps . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . .Keep Soils Healthy . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . .

Grow H ea lthy Plan ts . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . .

Monitor and Maintain the System . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . ..

III. Appendix Californ ia Gra ywater S tan da rds ......... . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . Graywater Measu res Check list ........ . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . Detergents List ........ . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . Historical Evapotra n sp iration Valu es in Inch es for J u ly......... . . . .. . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . .

iii

vii

1

2

2

2

2

3

5

6

6

7

8

8

10

11

11

11

11

13

14

14

14

16

16

16

17

17

17

1718

19

20

23

31

33

35


8/45


9/45

This report was wri t ten by:

Marsha Prillwitz................................................................................................Water Conservation Office

Larry Farwell. ..................................................................................................Water Conservation Office

With th e ass ista nce of:

Ed Craddock. ............................................................................................................Division of PlanningCarole Rains. . . . . . . .. . . . . . . .. . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. . . . . . .. .Pub lications an d Editorial Services

Write to: California Depar tmen t of Water Resour ces, P.O. Box 94283 6, Sacra men to, 94236 -0001 or cal lMarsh a Pril lwitz at (916) 327-16 20.


10/45


11/45

Why Use Graywater?

Are you t i red of watching you r ba thing an d lau nd ry water go down th e drain wh en i t

could be put to good us e on you r lan dscap e? Now it is sa fe and legal to reus e tha t

"graywater" and this gu ide sh ows you how.

In add it ion to cons erving water a nd probab ly reducing you r water a nd sewer bi lls ,

you will also be "drou ght-pr oofing" your lan ds cap e by u sing graywater. Since more th an

ha lf of you r indoor water can be reu sed a s graywater, du ring sh ortages, when ou tdoor

watering ma y be restricted, you will h ave a cons tan t sour ce of water. With lan ds cap es

valu ed at between 5 percent an d 10 p ercent of the valu e of a h ome, this back-u p su pply of

water may be an imp ortant economic ins u ran ce policy for you. Furth ermore, the nu tr ients

in graywater may be beneficial to your plants.

The seven steps to follow to pu t graywater to u se in your lan dscap e are:

1. Investigate the permit process

2. Prepare a plan

3. Design the graywater s ystem

4. Su bm it th e plan for review and app roval

5. Instal l the system

6. Arran ge for system insp ect ion a nd app roval

7. Use, mon itor and m aintain th e system

If you decide n ot to do some of the s teps yours elf, you can hire a lan dscap e contrac-

tor to ins tal l the i r r igat ion system or a plum bing contra ctor to ins tal l the plum bing. They

will follow this same process.

To bet ter i llustra te how to insta ll a residential graywater system , this gu ide featu res th e Brown

fam ily. In examp les th rough out the text , this family of four follows th e seven s teps.


12/45

The Seven Steps

Th e followin g seven s teps will h elp you p lan, d esign, insta ll, an d m ainta in your

graywater s ystem.

1. Investigate the Permit ProcessInform ation in th is guide is ba sed on th e California Graywater Stan dard s. In the

ap pen dix, you will find a copy of Title 24, Part 5, of the Californ ia Adm inistra tive Code,

GRAYWATER S YSTEMS FOR SINGLE FAMILY DWELLINGS, com m on ly ca lled th e C a lifor n ia

Gra ywater Sta n da rds (App end ix J ). Thes e are th e official ru les for u sing graywater in

California.

The Sta nd ards require that a bu ilding permit be obtained before a

graywater system is installed. Check with your local building depart-

men t for inform ation on th eir perm it process a nd an y var iat ions

ma de to the Graywater Stand ards before you proceed.

2. Prepare the PlanIs a graywater s ystem for you? By first learn ing

ap proximat ely h ow mu ch gra ywater your family will

produce an d h ow much land scape you can i r r iga te

with it , you will be bett er ab le to decide. Determ in-

ing wheth er your s oil is s u itable for a graywater

system is a noth er pr imary considerat ion. On ce you

ha ve decided th at a graywater system is in your

fu tu re, the next s tep is to draw a plan an d design

your system.

Estimate the Am ount of Gray w ater Your Family Will

Produce

The nu mb er of plum bing fixtures which you

connect to th e graywater s ystem wil l determine h ow

much graywater is available for irrigation use. See the

section entit led "Plu mb ing System : Pipes an d Valves"

page 8 for m ore inform ation abou t accessing plum bing

fixtures.

The Graywater Stan dard s u se th e following procedu re to est i -

m ate you r da ily graywater flow:


13/45

(1) Calculate the n u mb er of occupa nts of your h ome as follows:

Firs t Bedroom 2 occu pa n ts

Ea ch a dd it ion a l bed room 1 occu pa n t

(2) Est imated dai ly graywater flows for ea ch occupa nt are:

S h ower s, b a th t u bs a n d wa s h ba s in s (t ot al) 2 5 Ga l./ Da y/ Occu p a n t

Cloth es wa sh er 15 Ga l./ Da y/ Occu pa n t

(3) Mu lt iply the n u mb er of occupa nts by th e est imated graywater flow.

Exam ple: The Brown fam ily has a th ree bedroom hou se so the system m u st be designed for a mini-

mu m of four p eople. If al l fixtu res ar e conn ected, then each occupan t is as su med to produ ce 40

gal lons of graywater per da y, resu l t ing in a total of 160 gal lons each day.

The reas on graywater flow is ba sed u pon th e nu mb er of bedrooms rath er than theactu al nu mb er of people is th at th e nu mb er of bedrooms will rema in constan t , whi le the

number of people may vary over t ime.

Estimate the A m ount of Land scape You Can Irrigate

Graywater is distributed subsurface and will efficiently maintain lawns, fruit trees,

flowers, sh ru bs a nd grou nd covers . It can be u sed to i r r igate al l plants at your hom e except

vegetable gardens.

You d o not n eed to do th e followin g calcu lation a s p art of th e perm it process, b u t i t

will help you determine jus t h ow mu ch lan dscap e you r graywater will ir r igate an d h ow

ma ny plum bing fixtures you m ay want to hook u p to the system. On pa ge 6, you will find

specific informa tion a bou t determ ining th e m inimu m required i r r igated area.

You ca n est imate either th e squ are footage of the lan dscap e or the n u mb er of plants

which can be irrigated. Generally, estimating the square footage is more useful for lawn

areas an d su bsu rface dr ip ir r igat ion s ystems while est ima t ing the n u mb er of plants wou ld

be m ore u sefu l for t rees an d s hru bs ir r igated b y a m ini- leachfield s ystem.


14/45

Use this form u la to est ima te the squ are footage of the lan dscap e to be irrigated:

LA = GW

ET x PF x 0.62

where:

LA = lan dsca ped area (squ are feet)

GW = est imated graywater produ ced (gallons per week)

ET = evapotra ns pirat ion* (inches per week)

PF = plant factor

0.62 = conversion factor (from inches of ET to gallons per week)

*Evapotran spirat ion is the am oun t of water lost th rou gh evaporat ion (E) from th e soil and

tra n sp iration (T) from th e plan t. (This form u la does n ot accou n t for irrigation efficiency. If your

irrigat ion system does n ot distribu te water evenly, extra wat er will need t o be a pplied.)

Exam ple: If the Brown fam ily living in Sacram ento pr odu ces 160 gallons of graywater per da y, howmu ch lawn can be i rrigated with th at graywater? (160 x 7 d ays = 1120 gal lons p er week)

LA = 11 20

2 x .8 x 0.62

LA = 1129 square feet

Since Sa cramen to ha s an ET of 2 inches p er week in J u ly (the pea k i r r igat ion m onth

in m ost a reas of Californ ia), th e Brown fam ily can irrigate 112 9 s qu are feet of lawn with th e

availab le graywater.

If the lan dscap e includes less water thirs ty

plants , more than twice as mu ch squ are footage can

be irrigated . For sp ecific informa tion ab ou t evapo-

transpirat ion and est imat ing landscape water

n eeds, see Un iversity of Californ ia Leaflet 2 149 3,

Estimating Water Requirem ents of Lan ds cape

Plantings , and U.C. Water Use Classification of

Landscape Species . These p u bl icat ions can be

obta ined th rou gh your cou n ty coopera tive extens ion office. Also, in th e ap pen dix, you will

find a l ist of evapotran sp iration rat es for th e mon th of J u ly for selected sites in Californ ia.

An al ternat ive to consider ing th e squ are footage of the lan dscap e is to est imate th e

nu mb er of plants tha t can be i r r igated with this 11 20 gallons of graywater p er week. Here is

a look-u p cha rt to help you determ ine a pproxima tely how mu ch water a n ind ividu al t ree or

sh ru b will need for one week du ring Ju ly:


15/45

Clim ate Re lat ive Wate r Nee d of Plant Gallon s Pe r Wee k

(Plant Fac t or) 2 0 0 SQ FT 1 0 0 SQ FT 5 0 SQ FT

CANOPY CANOPY CANOPY

Coa s ta l low wa ter u s in g (0 .3 ) 3 8 19 10

(ET=1 in / wk) m ediu m wa ter u s in g (0 .5 ) 62 31 16

h igh wa ter u s in g (0 .8 ) 10 0 50 25

In la n d low wa ter u s in g (0 .3 ) 7 6 38 19


h igh wa ter u s in g (0 .8 ) 20 0 100 5 0

Des er t low wa ter u s in g (0 .3 ) 114 57 28


h igh wa ter u s in g (0 .8 ) 30 0 150 7 5

[The gal lons per week ca lcu lat ion for this char t was determ ined with th e fol lowing formu la:Gallons per week = ET x plan t factor x area x .62 (conversion factor.)(This form u la does n ot accoun t

for irrigation efficien cy. If your irrigation s ystem does n ot distr ibu te water evenly, extra water will

need to be applied.)]

Exam ple: The 11 20 gal lons of graywater per week produ ced by the Brown fam ily in Sacram ento

could irrigate:

8 you ng fru it t rees : 8 x 50 = 400 ga llon s (h igh wa ter u sin g, 50 foot ca n opy)

8 m ediu m-s ized sh ade t r ees : 8 x 62 = 496 (m ediu m wa ter u s in g, 100 foot ca n opy)

7 la rge s h ru bs : 7 x 31 = 217 (m ediu m wa ter u s in g, 50 foot ca n opy)

tota l: 11 13 ga llon s per week

The number of gallons of water per week a plant needs will vary from season to

seas on, plant to plant , an d s ite to s i te, bu t th is will give you a general idea abou t th e

nu mb er of plants you can su ccessfu lly ir r igate in J u ly with you r graywater.

Ir r igat ion n eeds of the land scape ma y be greater th an the total avai lable graywater .

So, even i f the system includes th e shower, tub a nd clothes wash er, some su pplementa l

water would be necessary dur ing the hot su mm er months . Cont rar i ly , the am ount of

ava ilab le graywater may be grea ter tha n the am oun t you can u se on th e land scape . In tha t

case, you can r edu ce the nu mb er of plum bing fixtures conn ected to the graywater system.

Gathe r Soil an d Groun d Wa ter Data

Determine the soil types and ground water level on your property. The local building

depa rtm ent will prob ab ly provide th is in form ation or allow you to u se Table J -2 of th e

Graywater Standards. If this information is not available, consult with the local building

departm ent ab out th e approved soi l test ing method. They may require that you h ire a


16/45

qu alified p rofess iona l to con du ct a p ercolation tes t, or m ay allow you to do it . Usu ally you

would be required to dig test holes in close proximity to any proposed irrigation area and

conduct a percolation test. The U.C. Cooperative Extension Office, the county agricultural

agen t or a local geologist, soil scientist or college ins tru ctor will be a ble to as sist with soil

type identification and characteristics. The United States Department of Agriculture Soil

Cons ervation Service pu blish es a Soil Su rvey of every coun ty which m ay be h elpful for th is

purpose .

Draw a Plot Plan

A plot plan of you r property sh ould be drawn to scale an d m ay be required to in-

clude dimensions, lot l ines, direction and approximate slope of the surface. The location of

retaining wal ls , dra ina ge cha nn els , water su pply l ines, wells , pa ved areas , an d st ru ctures

sh ould be included. I f you ha ve a sept ic tan k, sh ow the locat ion of you r sewage disposal

system an d the requ ired 100 percent expan sion a rea. Provide inform ation on th e nu mb er of

bedrooms an d wh ich p lu mb ing f ixtures will be connected to

the proposed graywater system. Final ly, ind icate th e land-scap e area tha t you p lan to ir r igate with graywater.

Determ ine the Size of the Irrigated Area

Above, you learn ed h ow to est imate th e am oun t of

lands cape you can ir r igate ba sed on th e graywater pro-

du ced an d the water n eeds of the plan ts . Now you n eed to

determine the minimum size of the irrigation field required,

bas ed on s oil type. With either a su bsu rface dr ip or m ini-

leachfield system , at least two irrigation zones are requ ired

an d each m u st i r r igate enou gh area to dis t r ibute al l the

graywater p rodu ced da ily withou t s u rfacing.

For su b-su rface dr ip i r r igat ion s ystems, Table J-3 of

the Graywater Stan dard s is us ed to determine the nu mb er of emit ters required. The em it-

ters mu st be at least 14 inch es apa rt in a ny direct ion.

Exam ple: The Brown fam ily produces 16 0 gal lons of graywater per day and irrigates plan ts in a

san dy loam s oil . Based on Table J -3, the minimu m n u mb er of emit ters per gallons per da y of graywa-

ter produ ction is .7 x 160 = 112 em it ters. With at least 14 inch es between each emit ter, the total

i rrigat ion a rea for one zone would be 112 emit ters x 14 inch es / 12 inch es (to get squ are feet) = 130

squ are feet . The Browns would need 13 0 x 2 = 260 squ are feet for the m inimu m of two irrigat ion zones

requ ired by the Graywater Stand ard s to safely distribu te their graywater withou t su rfacing.

As we discovered earl ier, the Browns could i rrigate u p to 1 129 squ are feet of lawn with 16 0 gal lons of

graywater per da y. Therefore, they can design th eir system to i rrigate over four t imes th e minimu m

irrigated area in this case an d st i ll ma intain a h eal thy lan dscap e.


17/45

If the mini-leachfield irrigation system is used, the required square footage is deter-

mined from Table J-2 of the Graywater Stan dard s.

Exam ple: The Brown fam ily produ ces 160 gallons of graywater per day an d is i rrigat ing a san dy loam

soil. Based on Table J -2, th e minimu m squ are feet of i rrigat ion area for a mini-leach field s ystem

would be 40 squ are feet per 100 gal lons, (160 / 100 =1.6)1.6 x 40 = 64 squ are feet . The Browns would

need two irrigat ion zones, each 64 squ are feet in s ize, a total size of 128 s qu are feet .

The Browns wan t to insta l l a 1 00-foot line with a t ren ch th at is 8 inches wide to irrigate th e 8 frui t

t rees an d 7 large shru bs a long th e perimeter of their yard. Then , they want to ins tal l an 80 foot line

with a t rench tha t is 1 foot wide to i rrigate 8 ma tu re sh ade t rees. To calculate th e area of the mini-

leachfield i rrigat ion field, th e length of the l ine as well as th e width of the t rench mu st b e considered.

Therefore, the tota l area of the irrigation field would be 6 6 s qu ar e feet (10 0 ft. length x .66 ft. width ) +

80 squ are feet (80 ft . length t imes 1 ft . width ) = 146 s qu are feet . Since 146 squ are feet is greater th an

the m inimum required i rrigated a rea for a mini-leachfield (128 squ are feet), an d s ince each zone is

grea te r than the requi red 64 s quar e fee t, the Browns meet the minimum ir r iga ted a rea requi rement .

Determ ine Location of the Grayw ater Sy stem

Once you know the size of the irrigation field, based on the soil and plant needs,

you can d ecide where to put i t . Table J-1 in th e Graywater Stan dard s estab lish es dis tan ces

tha t the s u rge tank a nd ir r igat ion f ield h ave to be from variou s featu res , su ch a s bu ildings,

sept ic tanks , an d th e domest ic water line. In a ddi t ion, you r system m u st be designed s o

th at n o irrigation p oin t is with in five vertical feet of th e highest k nown sea son al grou n d

water.


18/45

3. Design the Graywater System The next step is to determine the different components of your graywater system

and prepare a description of the system itself. Included will be a determination of the

irrigated area and details of the graywater system. This construction plan includes a de-

scription of the complete installation including methods and materials.

A graywater system us ually consists of :

Plumbing System made up of pipes and valves to bring the graywater out of the house

Surge tank to temporarily hold large drain flows from washing machines or bathtubs

Filter to remove particles which could clog the ir rigation sys tem

Pump to move the water from the surge tank to the irrigation field

Irrigation System to move the water to the plants

It may be helpful to refer to Figure 1 in the Graywater Standards to get a sense of

the overall layout of a graywater system. Then continue reading this section which de-

scribes the different parts needed to assemble your system. In your plan, all of the parts ofyour graywater system must be identified as to the manufacturer.

Plumbing Sy s tem: Pipes a nd Valves

The plumbing fixtures which can be used easily in a graywater system depend on

the buildings foundation. If your home is built on a slab foundation, most drain pipes are

buried beneath the concrete slab and the graywater from the bath and shower are unus-

able without expens ive remodeling. H owever, if your wash ing mach ine is located near an

outside wall or in the garage, the water is easily usable.

If your home is built on a raised foundation, the drain pipes are generally accessible

from the crawl space. B efore you enter the crawl s pace, draw a floor plan of your hous e,

noting the location of the shower, bath, washing machine, and bathroom sinks. Under the

house, identify which drain lines serve which fixtures and decide which ones you would like


19/45

to include in your system. The more fixtures included in the graywater collection system,

the more graywater you will have, but the more plumbing changes you will have to make. If

you are remodeling your home, this is a great time to access the plumbing and install a

graywater system.

The Graywater Standards require that all graywater piping be marked "Danger-

Unsafe Water." This is usually done by wrapping the pipe with purple tape, which is avail-

able at most irrigation supply stores. You can install graywater plumbing to a new house

for future graywater use even though you are not quite ready to install the irrigation sys-

tem. This capped off, preliminary plumbing, often referred to as "stub-out plumbing," is

allowed in the Graywater Standards as long as it is properly marked.

All valves in the plumbing system must be readily accessible, and backwater valves

mus t be installed on s urge tank drain connections to san itary drains or s ewers. F inally,

piping mus t be downstr eam of a waterseal type trap.

Here is one example of how graywa-

ter can be moved from the home to a

mini-leachfield system.


20/45

Surge Tank

Where a graywater pipe exits the homes foundation,

i t is rou ted to a su rge tan k. The tan k can be located near

the h ouse or , if the l ine is run u nd ergroun d, nearer th e

irr igat ion a rea. The tan k m u st b e solid, dura ble, water t ight

when filled, an d pr otected from corrosion. The tan k m u st b e

vented a nd h ave a locking gasketed lid. It mu st be an -

chored on d ry, level, comp acted soil or on a th ree-inch

con cret e slab. The cap acity of th e tan k an d "GRAYWATER

IRRIGATION SYSTEM, DANGE R- UNSAFE WATER" mu st be

perman ent ly marked on the t an k . The tank d ra in an d

overflow gravity drain m u st b e perm an ent ly conn ected to

the sewer line or septic tank. The drain and overflow pipes

mu st not be less in diameter than the inlet pipe.

This illustration shows a typical

hook up f rom the home to a

subsurface dr ip system.


21/45

Filter

For su bsu rface dr ip i r r igat ion s ystems, a 140 mesh (115 micron) one inch filter with

a cap aci ty of 25 gal lons p er minu te is requ ired. A mesh size of 140 mean s th at a screen h as

140 openings per squ are inch. The s ize of the openings a re 115 m icrons (a m icron is equal

to one-thous an dth of a m illimeter) each, which is equivalent in m easu re to a 140 mesh .

Pump

If all of th e plan ts you wish to irrigate with gra ywater a re below the b u ildings d rain

lines, th en th e graywater s ystem a nd ir r igat ion lines could u se gravity to dis t r ibute the

water . If an y of the plants you wish to ir r igate with graywater a re h igher th an the su rge

tan k or th e bu ildings d rain lines you will need a s ma ll, in expens ive pu mp to lift th e water

to the plants. A pump will increase the cost of the system slightly .

To pick the r ight s ize pum p you m u st kn ow:

1. th e h ead (th e total lift mea su red in feet from t he p u mp to the h ighes t point in

the lan dscap e) of you r s ystem;

2. the d is tan ce from th e tan k to the fur th est point you wish to i r r igate; an d3. th e ma ximu m discharge rate of al l you r graywater sou rces.

For both dis tance an d h ead, th e pu mp s sp ecificat ions mu st sh ow a gal lon-per-h our

(gph) or gallon-per-m inu te (gpm) rate . Make su re tha t th e rat ing is a t least 10 gpm at th e

hea d you will be us ing. Try to get a pu mp tha t does n ot need water cooling so th at a ll the

water can be pu mped out of the t ank . Buy a pu mp tha t m eets or exceeds your needs .

Check th e ma nu factu rer 's specificat ions .

Irrigation System

The Graywater Standards allow for two kinds of irrigation systems to be used for

graywater: su b-su rface drip irrigation or mini-leach fields.

Su bs urface Drip Irrigation S y ste m

Here is a descr ipt ion of the var ious par ts of a s u bsu rface dr ip i r r igat ion s ystem:

Emit ters: The m inimu m flow path of the emit ters is 120 0 microns (the h oles can be

no smaller than 1200 thousandths of a millimeter in size). The coefficient of manu-

facturing variation (Cv) can be no more than 7 percent. Cv is a method of describ-

ing how evenly the emitters apply water at the time they come from the factory.

According to th e Am erican Society of Agricu ltura l Engineers, good em itters h ave a

Cv of 5 percent or less , average emit ters a re between 5 an d 10 percent , an d m ar -

gina l emit ters are between 10 a nd 15 percent . Em it ters mu st be recommen ded for

su bsu r face and graywater u se an d dem ons t ra te res is tan ce to root in t ru s ion .

(To determine the emitter ratings of various products, check with your local building

departm ent or order a copy of the Irr igat ion Equ ipm ent Performa nce Report , Drip

Emitters and Micro-Sprinklers , from th e Cen ter For Irrigation Techn ology, Ca liforn ia

State Universi ty, 573 0 N. Chestn u t Ave., Fresno, CA 9374 0-0018 , (209) 278-2066 .)

Su pply lines: PVC class 200 p ipe or bet ter and s chedu le 40 fit t ings m u st be u sed


22/45

for al l su pply lines. J oints , when properly glu ed, will be ins pected an d p ressu re

tested at 40 p si and m u st rema in d r ip t ight for 5 m inu tes . All su pply lines m u st be

bu ried at least 8 inch es deep.

Drip lines: Poly or flexible PVC tu bing sh all be u sed for drip lines wh ich mu st b e

bu ried at least 9 inch es deep.

Pressu re reducing valve: Where press u re at th e discha rge s ide of the pu mp exceeds

20 pou nd s per squ are inch (psi) a press u re reducing valve mu st be u sed to maintain

pressu re no grea te r than 20 ps i downst ream from the pu mp a nd before any emis-

sion device.

Valves, switch es, t im ers, an d other contr ollers: These devices are us ed, as ap propr i-

ate , to rotate th e dis t r ibu t ion of graywater between i r r igat ion zones a nd to schedu le

the irrigations.

Au tomatic flu sh valve/ vacu u m b reaker: These devices are required to prevent ba ck

syphonage of water and soil .


23/45

Mini-Leachfield Sy s tem

Th e dimen sion sp ecifications of th e mini-leach field are foun d in th e Graywater

Sta nd ard s, Section J -11 (b) (3). Here is a d escription of th e variou s pa rts of a m ini-

leachfield system :

Perforated pipe: The pipes mu st be a minimum 3-inch d iam eter, cons tru cted of

per forated high d ens ity, polyeth ylene, ABS, or PVC pipe, or other ap proved ma terial.

The m aximu m length is 100 feet ; minimu m s pacing between l ines is 4 feet ; and the

ma ximu m grade is 3 inch es per 100 feet .

Filter ma terial: A clean s tone, gravel, or similar m ater ial, sized between 3/ 4 an d

2-1/ 2 inches, m u st be u sed. This filter mater ial is th en covered with lan dscap e

filter fabric or similar porou s m ater ial before being covered with ea rth . Do not

backfill the t ren ch u nt i l af ter i t has been ins pected.


24/45

4. Submit the Plan for Review and ApprovalOnce you h ave comp leted th e app licat ion form, plot plan , constru ct ion plan , an d

soil and groun d water determ ina t ions, s u bm it them to the bu ilding depa rtmen t . Staff will

review your su bm it tal to ins u re tha t you are in complian ce with th e Graywater Stan dard s.

Most l ikely, th ey will h ave a form listing th e pr ovisions of th e Graywater Sta n da rds an d will

check off each item a s th ey determine i t conform s with th e regulat ions. In the Appendix

you will find a sample Graywater Measures Checklist on page

31. On ce your s u bm it tal is a pproved, you m ay begin ins tal la-

t ion of you r graywater system . Remember th at th e bu ilding

insp ector will wan t to insp ect you r system before you cover

the subsurface drip irrigation lines or backfill the mini-

leachfield trenches.

5. Install the SystemPurcha se the Equipm ent

Your constru ct ion p lan includes a descr ipt ion of the

m aterials to be u sed for the graywater s ystem. This will form

th e ba sis of your "sh opping list ." On t h e followin g page is a

sh opping lis t for th e system th e Brown Fam ily plan s to

install .

In m os t cases , the p lumbing par t s , pum p an d tan k can be pu rchased a t your loca l

plum bing su pply store. Look in th e Yellow Pages u n der "Plu m bing Fixtu res, Part s, an d

Su pp lies, Reta il." The Yellow Pages a lso ha s listings for "Pum ps -Dealers" and "Tank s-Fiber

Glass , Plas tic, Etc," or "Tank s-Metal" if your first s top does n ot ha ve all th e pa rts you need ."Irr igat ion Systems an d Equ ipm ent" is th e h eading to look un der for the compo-

nents of the subsurface drip irrigation system. The pipes for a mini-leachfield system can

be pu rcha sed from a plum bing su pply s tore an d th e gravel fi lter ma ter ial can be fou nd at a

"Sa nd an d Gra vel" compa n y, listed as s u ch in th e Yellow Pages.

There ar e some special ty s ign compa nies tha t produ ce the warn ing labels su ch a s

"GRAYWATER IRRIGATION SYSTEM-DANGER-UNSAFE WATER," n eed ed for you r gra ywat er

sys tem.


25/45

Parts an d Approxim ate Cos ts for th e Brown Fam ily Graywate r Sys te m *

Part s Approxim at e Cos t ($ )

washing machine hook-up

conn ec tion par t s

th ree-way diverter valve

pipe to sewer

pipe to tan k

sani tary tee

shower / ba t h hook-up

conn ec tion par t s

pipe to tan k

be nds

fittings

vent

Total: Plum bing Part s $ 1 2 1

55 gallon tan k with l id

vent

inlet pipe

overflow pipe

dra in pipe

backwater valve

water seal type t rap

emergency drain ball valve

tank adap ters ($20 each, one for each pipe)

union

Total: Tank Part s $ 2 3 3

Total: Pum p $ 1 5 0

AND

Su bsu rface Drip Irrigat ion System

filt e r 140 mesh one- inch 25 ga l/ min

pipe: PVC class 200

fi t t ings: sch edu le 40

drip l ines : 112 emit ters

valves ($25 each)

au tomat ic flush valve ($2 ea ch)

controller

switches

pressure reducing valve

compres sion T's

Total: Drip Part s $ 2 5 3

OR

Mini-leachfield

solid p ipe

perforated pipe: 180 ft .grave l, 18 in / 130 ' / 1 ' = 7 yds .

landscape filter fabric

Total: Leac hfie ld Part s $ 2 3 0

GRAND TOTAL: DRIP $ 7 5 7

GRAND TOTAL: LEACHFIELD $ 7 3 4

*Cost for perm it fees, renta l equ ipment , pr ofessional ins tal lat ion, an d m aintena nce n ot includ ed.

20

28

4

4

3

15

4

15

15

13

10 1

13

4

4

4

4

3

28

60

12

25

12

15

46

50

4

50

32

15

4

50

7070

40


26/45

Ins tall the Plum bing Sy stem

Modifying drain lines usually requires extensive plumbing knowledge and skills;

seeking professional ass is tan ce is r ecomm ended. This gu ide does n ot provide ba sic plu mb -

ing instructions. If you are a do-it-yourselfer, the staff at a retail plumbing store, plumbing

books at the library, or friends may be able to provide you with the plumbing information

you will need for most of the plumbing work associated with a graywater system.

The drain pipes in h omes b u il t before 1970 are general ly cast i ron, while th ose bu ilt

s ince 197 0 will probably be plast ic . The tools requ ired to m ake th e n ecessary plum bing

cha nges will usu al ly include: a h acks aw, tape m easu re, flash light , h am mer, pipe wrenches

(meta l pipes on ly), an d scr ew drivers. An electric drill an d a h ole sa w ma y be necess ary to

provide access holes throu gh wal ls . I f you do n ot ha ve the n ecessary tools , m ost ren tal

compan ies r ent thes e tools inexpens ively. Be carefu l not to conn ect an y par t of the graywa-

ter system piping to th e exist ing water su pply system.

In order to clearly identify graywater pipes, all graywater l ines must be continuously

m ark ed along th e entire length of th e pipe with a wa rn ing lab el. Iden tification of graywater

pipes is importa nt to avoid th e poss ibility of cross-con n ectin g graywater pipes with freshwater s u pp ly lines . This is for you r protection a s well as for th e protection of fu tu re occu-

pan ts of you r h ome who m ay be u na ware of the exact locat ion of the graywater plum bing

an d is especial ly imp ortant with graywater pipes th at resem ble s tan dard fresh water su pply

pipes.

Ins tall the S ub s urface Drip Irrigation Sy s tem

Once a gain, th is guide provides a brief overview of th e ins tallation p rocess, n ot ba sic

land sca pe irrigation in stru ction s. You ca n ca ll th e local cha pter of th e Californ ia Lan ds cap e

Contr actor 's Ass ociation or th eir s tate office at (91 6) 448-25 22 for a l ist of qu alified refer -

rals to insta ll su bsu rface dr ip i r r igat ion s ystems.

If you decide to do it yours elf, first , gath er all the pa rts you h ave determ ined will be

n eeded for your s ystem . Th ere are s pecial tools for diggin g the tren ches for th e drip lin es, or

you can do i t with an ordinary sh ovel. After the t ren ches a re du g, it i s recomm ended tha t

you ins tall the m ain valve, fi lter, an d p ress u re regu lator first . Next, inst all of th e ma in PVC

lines an d fina lly the d rip lin es. On ce th e system is fu lly in sta lled, tes t i t for leaks. Don 't

cover the s ystem u nt i l it i s ins pected an d a pproved.

Ins tall the Mini-Leachfield Sy s tem

To creat e a m ini-leach field, dig a tren ch along th e driplin e (th e out er edge of th e

foliage) an d fil l i t with gravel to with in n ine inch es of the s u rface. Be su re to cover the

gravel with a land sca pe fil ter fab ric or similar m aterial before fill in g th e tren ch with soil. If

soil is ab le to in filtra te down into th e gravel, th e m ini-leach field will qu ickly clog an d t h e

water will be forced to th e su rface.


27/45

6. System Inspection and ApprovalOnce al l the p lu mb ing is conn ected, the tan k in place, an d th e ir r igat ion system in

the grou nd (bu t u ncovered), arra nge to ha ve a bu i lding ins pector come ou t for the fina l

ins pect ion an d ap proval . The insp ector will be checking that th e su rge tank r emains water-

t ight as the ta nk is f illed with water ; that a ll the lines rema in water t ight du ring a pressu re

test ; and th at th e other measu res lis ted on th e Graywater Measu res Checkl is t in the app en-

dix meet the Graywater Standards.

7. Using, Monitoring and Maintaining the SystemProtect H ea lth

If a m emb er of a h ou seh old is i ll , graywater m ay carr y in fectiou s ba cteria or virus es.

However, in order for th e graywater to m ak e an other pers on ill it would be n ecessa ry for

tha t person to dr ink or otherwise consu me th e conta minated graywater. As long as a per-

son does n ot dr ink th e graywater or ir r igate vegetables with graywater a nd then eat th em

u nwas hed, graywater is sa fe.

The Graywater Standa rds requi re tha t graywater not su r face and th a t h um ancontact with graywater be avoided. Graywater system s d esigned, ins tal led, an d m aintained

in a ccordan ce with th e s tan dar ds pres ent m inimal r isk to pu bl ic heal th. The Cal ifornia

Department of Health Services participated actively in the development of these standards

to ins u re th e protect ion of pub lic hea lth.

When graywater is used, always follow these rules :

Don't dr ink or play in graywater.

Don't m ix potable (drink ing) water with graywater.

Don't a l low anything th at ma y be eaten to come into contact with graywater.

Don't a l low graywater to pond on th e su rface or ru n off the property.

Select Garden-Friendly Soaps

Th e chem ical an d b iological

comp osition of gra ywater varies greatly,

based on n um erous fac tors , inc luding

th e original qu ality of th e water com ing

to your h ome, the persona l ha bi ts of

the family members , which plum bing

fixtures are conn ected to the system,

an d the soaps u sed . Since the type of

detergent you select is on e ma jor factor

tha t you can con trol, the u se of garden-

friendly soaps can contribu te signifi-

can tly to better qu ality graywater.


28/45

Most ha nd a nd d ish soaps a nd s ha mp oos will not dam age plan ts at low resident ial

concentrat ions. Laun dry detergents , on the oth er ha nd , need to be selected carefu lly.

Sodiu m a nd boron are ch emicals th at can ha ve a n egat ive effect on lan dscap es. Powdered

detergent s a n d s oaps include "filler" ingredients (n ot essen tial to clothes clean ing) which

are u su al ly some compou nd of sodium . Liqu id soaps contain few fillers , th u s less sodium .

A few soaps are n ow being form u lated for u se with graywater s ystems. Cleaners an d

lau ndry soaps you m ay wish to avoid are:

bleach es or softeners (send graywater to sewer when u sed)

detergents tha t a dvert ise wh itening, softening an d en zyma tic powers

detergents with ingredients wh ich include:

boron, borax, or chlorine, or bleach

peroxygen or sodiu m perborate

petroleum distil late or alkylbenzene

sodium trypochlorite

Often the labeling on detergents is incomplete. The University of Arizona Office of

Arid Lands Studies (with the sponsorship of Tucson Water) tested the composition of manycommon detergents for sodium , boron, ph osph ate, alkal ini ty, and condu ct ivity. High a lka-

linity often indicates a h igh level of sodiu m. Cond u ctivity is t he m eas u re of all diss olved

sa lts in th e water. The h igher the concentr at ion of sa lts an d m inerals , the greater th e

potent ial for adverse imp acts on the s oil and plants . Ph ospha tes ar e good for plant growth,

but the detergent form may not always be usable by the plants. The Office of Arid Lands

Stu dies su ggests th at you select detergents with th e lowest levels of alkalinity, condu ctivity,

boron, a nd sodium . This informa tion is inclu ded in th e Appen dix.

Generally, once people begin to use graywater, they think more carefully about what

they pu t down th e drain. Some clean ing produ cts are toxic to plan ts , people an d th e envi-

ronm ent a nd s hou ld n ot be used. Products designed to open clogged drains or clean porce-

lain without scrubbing m u s t be sen t to the s ewer or replaced with al ternat ive produ cts or

boiling water an d elbow greas e.

Also, home water softeners often use a solution that contains high levels of sodium

chloride tha t m ay h ave a n egative effect on s oils. Avoid us ing soften ed water as graywater

when possible.

Keep Soils Healthy

Sodiu m, potas sium an d calciu m a re alkaline ch emicals . Becaus e of the presen ce of

thes e chem icals in lau nd ry detergent , graywater u se ten ds to raise alkal ini ty of the soil.

Slightly alka line s oils will su pport m an y gar den plan ts. E ven mos t acid-soil loving plan ts

will be happy with slightly alkaline soils that are generously amended with organic matter.

The pH of an acid s oil is 6 .9 or lower while th at of an alkaline soil is 7 .1 or h igher. If a

simple pH test ind icates th at th e pH reading is over 8.0, th e pH sh ould be redu ced. This

can be accomplish ed by ad ding agricul tura l sulfu r or a n acidifying fer t i lizer su ch as am mo-

nium sulfate .

Problems with water infilt rat ion ma y be du e to a sodium bu ild u p in the s oil. Soil


29/45

an alyzed by a s oil lab is the on ly way to verify excess s odium . Depen ding u pon th e severity

of the problem, you can u su al ly correct it by adding agricul tura l gypsu m a nd / or organ ic

ma tter to th e soi l.

A sa n dy, well-dra ined s oil will be less affected by th e ap plication of graywater th an a

poorly drained clay soil . Sometimes graywater may degrade the structure of a clay soil by

m ak ing it stickier an d less loamy. The soil's ph ysical condition a lso ma y be affected by h igh

sodium. To correct these problems and keep soil healthy, once again, t i l l in organic matter.

The salts that might build up from the use of graywater will only be a problem if

th ey are not leach ed a way periodically by heavy rains. If win ter ra ins a re light, occas ion ally

leach th e soil with fresh water.

Grow Hea lthy Plants

Th e app lication of too mu ch wa ter, of an y kin d, too frequ ent ly will resu lt in s atu -

rated s oils , an d a n invitat ion to plan t disease. General ly, plan ts a re hea lthier when th e soil

is allowed to dry ou t between irrigations.

A very small percentage of plants may be damaged by graywater, most of these are

listed below. Too mu ch s odium or chlorin e could res u lt in leaf bu rn , chlorosis (yellow

leaves), an d twig die ba ck. Boron ca n be toxic to plan ts a t levels on ly slightly greater th an is

requ ired for good plan t growth. Symp toms of boron toxicity include leaf t ip an d m argin

bu rn , leaf cup ping, chlorosis , bran ch die back, prematu re leaf drop, an d redu ced growth.

Shade loving and acid loving plants do not l ike graywater. Their native habitats are

forested areas where acid soils pr edominate. Here are some plan ts th at a re not su i table for

the alkaline conditions often associated with graywater irrigation:

Rh ododen dron s Begon ia s

Bleed in g Hea r ts Fer n s

Oxa lis (Wood Sorrel) Foxgloves

Hydra n gea s Ga rden ia s

Aza lea s Ph iloden dron s

Violet s Ca m ellia s

Im pa t ien s Prim ros es

Other plan ts th at a re especial ly sus cept ible to high sodium, a nd chlor ide which ma y

be presen t in graywater are:

Crape Myrtle

Redwoods

S t a r J a smi ne

Holly

Deodar Cedar


30/45

Plants that would probably do well with graywater irrigation are:

Olea n der Ita lia n Ston e Pin e

Bou ga in villea Pu rp le Hopseed Bu sh

Fa n & Da te Pa lm s Oa ks

Rose Arizon a Cypres s

Rosem a ry Cotton wood

Aga p a n th u s Olive

Ber m u d a Gra s s Ice Pla n t

Hon eys u ck le m a n y n a t ive p la n ts

Au s tra lia n Tea Tree J u n iper

Monitor an d Maintain the Sy stem

If you h ave som eone else inst all you r graywater s ystem , th e insta ller will provide an

opera t ion an d m aintenance m anu al . That person will r ecomm end su ch pra c t ices as check-ing the pu mp , filters , ma in l ines, a nd other l ines to keep you r system in top condi t ion.

It i s imp ortan t to check your s ystem on a regular b asis , every week or so, to see that

graywater is not su rfacing, tha t the plants a nd s oils are h eal thy, an d tha t the equipmen t is

working pr operly.

The pu mp is a n impor tant par t of the graywater sys tem. Read th e pu mp's ins t ruc-

tion guide carefully. Adjust the pump's float switch to turn on as early as possible to avoid

an overflowing tan k. Be su re to connect th e grou nd ed, thr ee-pronged cord su ppl ied with

the pu mp to an approved Grou nd Fau lt In te rcept ou t le t . The pu mp run s off s t an dard h ouse

curr ent , s o special wir ing is n ot necessa ry.

A pu mp sh ould not be ru n without a ch eck-valve, which is ins tal led between the

pump and the first irrigation point. The check-valve allows water to pass in only one direc-

t ion-- toward the land scape, an d n ot back into the ta nk . Withou t a ch eck-valve, water

dra in ing back in to the t ank would ac t iva te the pu mp a nd the pu mp would run cont inu-

ously.

The main concern people have with drip irrigation systems is the possible clogging

of th e emitters, p reventing th e flow of water to th e plan ts. With prop erly selected an d

ma intained f ilt rat ion an d occasional flush ing of the su bsu rface dr ip i r r igat ion s ystem, m ost

prob lems with emitter cloggin g can be a voided. If clogging does occu r, simple chem ical

solu t ions can be u sed to clear th e emit ters .

Th e 3-way d iverter valve (or was h ing ma chin e "Y" valve) which was insta lled a s pa rt

of the graywater system a llows the graywater to be sent back to the s ewer/ sept ic line wh en

rain h as s atu rated th e soil. Tu rn ing th e graywater system off du ring the rainy season will

help keep th e soi l hea lthy becau se th e rain will leach away an y soap b u ildu p. The diver ter

valve is also employed to sen d water with cau st ic cleaners or s t rong bleaches to the sewer/

sep tic line.


31/45

Appendix


32/45


33/45


34/45


35/45


36/45


37/45


38/45


39/45


40/45


41/45

Graywater Measures ChecklistDescription Designer Plan Checker Inspector

Drawings and Specifications (J-4)

(J-4, a) plot plan drawn to scale showing:

lot lines and structure

direction and approximate slope of surface

location of retaining walls, drainage channels, water supply lines, wells

location of paved areas and structures

location of sewage disposal system and 100% expansion area

location of graywater system (Table J-1 lists required distances)

number of bedrooms and plumbing fixtures

(J-4, b) details of contruction: installation, construction, and materials

(J-4, c) log of soil formations, ground water level, water absorption of soil

(J-7) no irrigation point within 5 ft. of highest known seasonal groundwater

Estimating Graywater Discharge (J-6)bedroom #1 (2 occupants)

additional bedrooms (1 occupant)

showers, tubs, wash basins: 25 GPD/occupant

laundry: 15 GPD/occupant

Required Area (J-7)

at least two irrigation zones

each zone to distribute all graywater produced daily without surfacing

meets Table J-2 design criteria of mini-leachfield OR

meets Table J-2 design criteria for subsurface drip systems

Surge Tanks (J-9)

solid, durable material, watertight when filled, protected from corrosion

(J-5, a) anchored on dry, level, compacted soil or 3 inch concrete slab

meets standards for non-potable water

vented with locking gasketed access opening

capacity permanently marked on tank

"GRAYWATER IRRIGATION SYSTEM, DANGER-UNSAFE WATER"

permanently marked on tank

drain and overflow permanently connected to sewer or septic tank

Valves and Piping (J-10)

piping downstream of waterseal type trap

piping marked "DANGER-UNSAFE WATER"

all valves readily accessible

backwater valves on all surge tank drain connections to sanitary drain or sewer

(J-5, a) stub-out plumbing permanently marked


42/45

Description Designer Plan Checker Inspector

Graywater Measures Checklist

Subsurface drip irrigation systems (J-11, a)

minimu m 140 mesh (115 micron) one inch filter, with a 25 gpm capacity

filter back-wash to the sewer system or septic tank

emitter flow path of 1200 micronscv no more than 7%, flow variation no more than 10%

emitters resistant to root intrusion (see CIT list)

number of emitters determined from Table J-3, minimum spacing 14 inches

supply lines of PVC class 200 pipe or better and schedule 40 fittings, when

pressure tested at 40 psi, drip-tight for 5 minutes

supply lines 8 inches deep, feeder lines (poly or flexible PVC) 9 inches deep

downstream pressure does not exceed 20 psi (pounds per square inch)

each irrigation zone has automatic flush valve/vacuum breaker

Mini-leachfield systems (J-11, b)

perforated lines minimum 3 inches diameter

high density polyethylene pipe, perforated ABS pipe, or perforated PVC pipe

maximum length of perofrated line- 100 feet

maximum grade- 3 inches/100 feet

minimum spacing- 4 feet

earth cover of lines at least 9 inches

clean stone or gravel filter material from 3/4 to 2 1/2 inch size in trench 3 inch

deep beneath lines and 2 inches abovefilter fabric covers filter material

Inspection (J-5, a)

system components identified as to manufacturer

irrigation field installed at same location as soil test, if required

installation conforms with approved plans

Testing (J-5, b)

surge tank remains watertight as tank is filled with water

flow test shows all lines and componints remain watertight


43/45


44/45


45/45

Historical Evapotranspiration Values in Inches for July

North Central Coast monthly weeklyNovato

San Franc isco

Concord

S a n J os e

Monterey

San Lu is Obispo

South CoastalSan t a Ba r ba r a

Ventura

Los Angeles

Laguna Beach

San Diego

Central ValleyAuburn

Sacramento

Modesto/ Stockton

Fresno

Baskersfield

Redding

South InlandSan Fer nan do

Pasadena

Riverside

Ramona

San Bernardino

High DesertPalmdale

Lancaster

Victorville

Bishop

Independence

Low DesertPalm Springs

Coachella

Needles

El Centro

5 .9

4 .5

7 .0

6 .5

4 .3

4 .6

5 .5

5 .5

6 .6

4 .9

4 .6

8 .3

8 .4

8 .1

8 .4

8 .5

8 .5

7 .3

7 .1

7 .9

7 .3

7 .9

9 .9

11.0

11.2

7 .4

9 .8

11.6

12.3

12.8

11.6

1 .3

1 .0

1 .6

1 .5

1 .0

1 .0

1 .3

1 .3

1 .5

1 .1

1 .0

1 .9

1 .9

1 .8

1 .9

1 .9

1 .9

1 .7

1 .6

1 .8

1 .7

1 .8

2 .3

2 .5

2 .5

1 .7

2 .2

2 .6

2 .8

2 .9

2 .6

gray water manual, los angeles california

Documents