We will discuss here how we get purified water.
We know the rain water which is absorbed by the soil, goes under ground. This water gets purified as it goes down through different layers of the soil. We get this purified water as well water, hand pump water and tube well water. The water from these sources is safe for drinking. However water from rivers, pond, lakes, etc. needs to be purified for drinking purposes and domestic uses.
The following ways will help us to get purified water:
(i) We have noticed that sometimes water contains germs and diseases. Boiling kills the germs from the water. So boiled water after it gets cooled, it is considered safe for drinking purposes. Often ill persons are advised by the doctor to drink boiled and cooled water.
(ii) Water sometimes contains suspended impurities. Such water should be filtered. Filtration can done by passing the water through layers of gravel and sand, packed in a earthen pot.
(iii) However only boiling or filtering does not remove all the impurities. So, we must boil the water first, then after cooling, it should be filtered then, the germs and suspended impurities both are removed. Such water becomes clean and safe for domestic uses.
(iv) In towns and cities purified water is supplied to citizens. Water is collected from rivers or canal or through tube-wells and is collated in big tanks. A small quantity chlorine or bleaching powder is added to the water to kill the germs. This chlorine added water is sprayed into air to remove the odour. Finally it becomes safe for drinking. This purified water is supplied all over the city through pipelines.