Page 105 - ICSE Science 3 : E-book

dissolves a range of gases present in the air. Also, when it falls on the earth as rain,
the dust particles, germs and some other substances mix with it. This rain water

either fi lls the waterbodies or seeps into the ground.

Therefore, the water that is available on earth is not pure and fi t for direct use

as it contains mud, dirt, sand, germs and other harmful substances. It should be
cleaned before use. The substances that make something dirty or impure are

called impurities. The major types of impurities present in water are either soluble
or insoluble.

Types of impurities

Soluble impurities: Dissolved gases, salts, minerals and chemicals are some

impurities that are soluble in water and can change its characteristics. These are
called soluble impurities.

Insoluble impurities: Mud, dust, sand, clay, oil, plant and animal material do not

dissolve in water. These are called insoluble impurities.

Causes of water impurities

• When water is kept uncovered, germs, dirt and dust enter it making it impure.

• A huge amount of harmful wastes from industries and sewage enters the

waterbodies making them dirty.

• Various human activities such as washing, cleaning and bathing in waterbodies

makes them unfi t for use.

Purifi cation of Water

The presence of impurities in water make it extremely Did You Know!
unsafe for use. Drinking impure water can lead to Water fi lters and purifi ers
are used at home these days
several waterborne diseases such as cholera, typhoid
to obtain purifi ed and safe
and dysentery. Impure water must be cleaned or water for drinking.

purifi ed before using.

Water purifi cation is the process of removing harmful substances from water to

make it fi t and safe for drinking. Let’s know about some ways of water purifi cation.

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