Water 1

Water is the most important liquid we know. It is everywhere

we look. Water is in the ground and in the air that we breathe.

All animals, plants and humans need water to survive. Water

has formed our earth since its beginning. It also prevents the

earth from becoming too hot or too cold. Water never disap-

pears. We use the same water over and over again.

C H E M I S T R Y O F W A T E R

Water consists of very small molecules. Each of them has two hydrogen atoms

and one oxygen atom. The chemical formula of water is H20.

Water can be a solid, a liquid or a gas, depending on the temperature it has. At

32° F (0° C) water freezes and turns into ice. It expands and becomes lighter. As

a result ice floats on water. That is why you should let water out of pipes during

the wintertime because it may freeze and burst the pipes. At 212°F (100°C) wa-

ter boils and escapes as a vapour into the air. Between these two states water

is a liquid. Most of the world’s water is in liquid form. It can be found every-

where on earth.

Water molecules always move. In ice they are very far apart from each other .

They move very slowly or often not at all. Molecules in water vapour move very

quickly.

W A T E R I N O U R D A I L Y L I V E S

Water has been important for people for thousands of years. Without water

there would be no life on earth.

We use water in our houses for cooking, bathing and washing the dishes. Water is

used to grow food. In many dry areas farmers must bring water to the fields

through canals and expensive irrigation systems.

Industries and factories also use water. Fruits

and vegetables must be cleaned before they can

be processed and sold in supermarkets. Water is

used for cooling in many areas, for example in

steel production.

Many countries around the world use water to

produce energy. Power stations burn coal which turns water into steam. Coun-

tries with many mountains and rivers use the power of water to produce elec-

tricity.

Water is important for our free time. People enjoy themselves at seaside resorts

or on cruise trips .

Transportation was at first carried out on waterways. Ancient civilizations

traded goods across the Mediterranean Sea. Today oil, coal, wheat and other

products are transported on waterways.

W O R D S

ancient = old

apart = away

boil = when a liquid becomes hot and

turns into gas

breathe = to take air in through your

lungs

burst = split open, break apart

carry out = to do something

coal = a hard black mineral that you dig out of the ground and burn to

produce heat

consist of = is made up of

cruise = holiday journey by boat

depend = affected by

disappear = go away

electricity = the power that is in cables or wires ; it give sus light,

heat and makes machines work

escape = get away

expand = grow or get bigger

float = drift, swim

goods = products

humans = people

hydrogen = the lightest of all gases; it forms water when combined with

oxygen

irrigation system = to bring water on

fields

liquid = a watery substance

Mediterranean Sea = sea between

Europe and Africa

oxygen = a gas that has no colour or

smell; it is in the air that we breathe

pipe = a tube through which gas or a

liquid flows

power station = building where elec-

tricity and energy is produced

prevent = to stop something from

happening

process = to make food better by

adding chemicals to it

seaside resort = holiday towns near

the coast

solid = an object that has a fixed

shape, not a gas or a liquid

steam = the hot gas that water pro-

duces when you boil it

steel = strong metal made out of iron

survive = to live on

vapor = gas

water vapor = water in the form of

small drops in the air

waterway = places where boats

travel

wheat = plant that you make white

bread from

Water 2

W A T E R A N D T H E H U M A N B O D Y

The human body is made up largely of water. Up to 75% of our body is water.

Water helps us digest food. Chemical reactions in our body would not be possi-

ble without water. It also needs water to help carry away the substances that

we do not need any more. Water regulates our body temperature so that it al-

ways stays the same. Although we can live without food for a few weeks without

water we would die within a few days. A normal human needs about 2 to 3 litres

of water a day to survive.

W O R L D W A T E R S U P P L Y

The amount of water we have on earth is always the same. However, clean wa-

ter, is getting rarer because of pollution.

Most of the world’s water, about 97% is in the oceans. 1.4 billion cubic kilome-

tres is saltwater. Only 3% is the freshwater in lakes, rivers and glaciers.

Much of the world has enough fresh water but there are regions that are too dry

and don’t get enough rain. Developing countries often do not have enough wa-

ter for their growing populations. Other areas do not have enough water be-

cause people waste it.

W O R D S

although = while

billion = a thousand million

blood stream = tubes in your

body through which blood passes

carry away = take away

chemical reaction = chemicals mix and change into new materi-

als

constipation = it you have prob-lems getting rid of the solid

waste from your body

developing countries = a poor country that is trying to make its

economy grow

digest = to change food that you have eaten into substances your

body can use

dissolve = to mix with a liquid

and become part of it

flush =wash out

freshwater = water from rivers

and lakes

glacier = large mass of ice that moves slowly down a mountain

valley

largely = mostly

lubricate = to make something

move more smoothly

nutrient = a chemical or food that gives plants and animals

what they need to grow

pollution = the process of making

air and water dirty

population = the people that live

in a country

prevent = stop

protect = defend

rare = not found very often

regulate = control

substance = material

survive = to live on

tissue = the material that forms

cells

waste = material that you cannot

use and do not need any more

waste = to throw something away

even if you can still use it

Water 3

W A T E R C Y C L E

Water moves in a steady cycle. It never goes away or disappears but it

changes from solid to liquid to gas.

When the sun heats up water it becomes a gas and evaporates. As it

rises it cools down and clouds form. Clouds have many very small

droplets of water in them. When they get too heavy they fall down to

the ground as rain or snow.

Although some of this precipitation rises directly into the atmosphere

again most of it gets into the ground and remains in aquifers. Snow

and ice remain on glaciers and ice caps until it gets warmer. Then it

starts melting and the liquid follows into lakes and rivers.

Water has shaped the surface of the earth for many years. It causes

erosion, makes mountains smoother, rivers carve themselves into val-

leys and makes them wider . Ocean waves form coastlines.

although = while

aquifer = underground layer of water

atmosphere = the mixture of gases that is

around the earth

carve = cut

coastline = where the sea meets land

disappear = go away

droplet = very small drop

erosion = when rock or soil is destroyed by wind,

rain or the sea

evaporate = liquid changes into gas

glacier = large mass of ice that moves slowly

down a mountain valley

ice cap = an area of thick ice that covers the

earth’s pole

liquid = a watery substance

melt = to turn from solid into liquid

precipitation = rain or snow that falls onto the

ground

remain = stay

shape = form

smooth = round, flat

solid = an object that has a fixed shape, not a

gas or a liquid

steady = stable, always the same

store = keep, save

surface = the top layer of

valley = lower land between two mountains ,

usually with a river flowing in-between

Water 4

W A T E R T R E A T M E N T

Not all water is safe to drink or to take a bath in. Some of it needs to be

cleaned or purified before we can use or drink it. This is done in three basic

steps:

1. Water first flows through a basin which has chemicals in it . The

bacteria, mud and other dirty substances that are in the water

stick to these chemicals and move down to the bottom of the ba-

sin.

2. Water then goes through a filter made up of sand and gravel.

Other particles are filtered out.

3. In the last phase chlorine is added to the water. It kills the bacte-

ria that somehow get through.

Dirty, used water is carried away through sewage systems. It often smells bad

and has a lot of bacteria in it. Most cities have treatment plants that turn used

water into clean water that can be used to irrigate fields.

W O R D S

bacteria = very small living

things, some of which cause ill-

nesses and diseases

basic = main, important

basin = very big, round container

chlorine = a greenish-yellow gas

with a strong smell; it is used to

keep water in swimming pools

clean

flow = run through

gravel = small stones

irrigate = to bring water onto

fields

mud = wet, sticky earth

particle = very small piece of

something

plant = place where something

happens

purify = to make clean

sewage system = waste from the

human body together with water

that is carried away from houses

through pipes

stick to = fix, glue, attach

substance = material

used = not new

water treatment plant = place

where dirty water is cleaned

Water treatment plant