Question

Name the steps involved in the purification of drinking water supplied in cities and towns.

Answer 1

The water source for our towns and cities are river, lakes or underground water which contains suspended and dissolved impurities.

To remove these impurities steps involved are:

1. Loading and sedimentation : to settle the suspended impurities to form a sediment for this purpose potash alum is added.

2. Filtration : The water still contains lighter suspended impurities which are removed by filtration through sand and gravel. In cities ground water is drawn from tube well or submersible pumps which have filters fitted in them. This clear water still contains germs.

3. Chlorination : To kill germs water is passed into chlorination tank where it is treated with chlorine to kill germs.

Water is now potable i.e. safer for drinking and supplied to homes.