Question

How is the river water converted into potable water, for city supply system?

Answer 1

SOURCE ⇒ SEDIMENTATION ⇒ FILTRATION ⇒ CHLORINATION ⇒ TO CITY

Potable water - The water that is fit for human consumption is called potable water.

The river water is converted into potable water by following steps -

A. SEDIMENTATION -

1. The process of settling down suspended impurities present in water is called sedimentation.
2. The water is collected in a tank and allowed to settle down.
3. This process can be accelerated by the addition of chemicals like alum and lime to form sticky precipitates that settle down at the bottom of the tank.

B. FILTRATION -

1. The water after sedimentation is much clear, but still, some suspended impurities are left behind.
2. To remove these impurities the water is passed through a bed of fine sand, activated charcoal, and gravel to remove the suspended impurities and bad odor.

C. CHLORINATION -

1. The water after filtration is clear and free from any type of suspended impurities, but it contains germs and bacteria that can cause diseases.
2. To kill all the germs and bacteria water is treated with chlorine gas. this process is called chlorination of water.

SUMMARY -

• Water from the source is first subjected to sedimentation.
• Then the water is filtered to remove any suspended impurities left after sedimentation.
• Finally to kill germs and bacteria the water is treated with chlorine by the process of chlorination.