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

Steps involved in the purification of drinking water are:

1. Loading and sedimentation — Running river water is permitted to flow into basins, tanks or reservoirs. Most of the suspended matter settles to the bottom as sediment. They are made to settle down more quickly by loading with the addition of a chemical known as potash alum.
2. Filtration — The water after sedimentation still contains some lighter suspended impurities which are removed by filtration through beds of sand and gravel. This leaves a perfectly clear water but it still contains germs.
3. Aeration — Air under pressure is then blown into the filtered water. This process is called aeration. It kills harmful micro-organisms present in the filtered water.
4. Chlorination — Water is then passed into a chlorination tank where it is treated with chlorine to kill all the germs present in it. Water is now potable or safe for drinking.
5. Storage — The potable water is then stored in a storage tank from where it is supplied to homes through pipes.