Page 57 - Health & Physical edu- 8

water of our taps and well may become undrinkable due to mixture of clay and
various micro-organisms may spread in it. Such type of contaminated water can be
purified adopting the following methods.

1. Boiling

The water can contain harmful micro – organisms though it looks neat and clean.
In such a condition, boiling method can make it drinkable.

2. Filtering

Polluted water can be made drinkable by filtering it. We can use water filtration
method easily at home as well. Filtration can make water look clean but household
filter cannot make it germs free. Water thus filtered can be drinkable only after
boiling it.

3. Chemical Method

While purifying water through chemical method, some drops of chemical are mixed
in the water in order to kill micro- organisms contained in it. Such chemicals are
used to kill the germs that cause cholera, dysentery, typhoid and diarrhea.If we
mix two drops of chlorine or iodine in one liter of water, the water becomes germs-
free after thirty minutes. Water purified through this method should not be used
by pregnant woman. Water may become poisonous if it contains more amount of
chlorine and iodine. Therefore, we should be careful about the amount of chemical
while applying this method.

4. SODIS Method (Solar Water disinfection System)

Even the visibly clean water may contain harmful micro – organisms. Such water can
be made safe and drinkable through SODIS method. The ways of purifying water
through this method are as follows:

a. First of all, wash colorless plastic bottles properly.

b. Fill water in such bottles, tighten the lids and shake well.

c. Then, put the bottle in the sun for six hours keeping at the temperature of
minimum 45°C.

d. Drink water directly pouring into a clean glass.

Health & Physical Education, Class-8 53