ENVIRONMENT AND HEALTH-

The main sources of water supply are-
1) Rain water or snow water and artificial lakes.
2) Surface water eg. Canals, rivers, tanks and ponds
3) Upland surface water eg. Lakes
4) Ground water eg. Wells and springs
5) Sea water
1) Rain water is pure initially; however it receives impurities from the atmosphere such as dust, soot, suspended matter, microbes, gases etc. Normally it is not pathogenic. Rain water if properly collected and stored is a safe water. It is soft as it contains no minarl salts in it. It is suitable for cooking, washing and bathing. It is soft and liable to corrode lead pipes and thereby cause lead poisoning.
2) Rain water on reaching the ground , or the melted snow from hills begins to flow as a river, canal, stream, lake or a pond and is called surface water. Since it may travel a long distance, it contains suspended materials. The water from these sources is collected in large reservoirs or settling tanks. Subsequently water is filtered and sterilized further by chlorination or other methods to make it suitable for drinking.
3) Upland surface water runs on the side on hills, slopes and valleys and is taken off as water supply before it forms big streams and rivers. An upland water is safe because it is pure rain water which has travelled a short distane. It needs purification by running through a bed of fine sand before final storage.
4) Wells and springs are important sources of ground water. An ideal well should be tapped in a good soil and should be at least 200ft. away from possible contamination source. No washing of clothes, utensils and bathing of persons be allowed near a well. Well-water may be treated with solution of 1 part of freshly prepared lime to 4 parts of water or bleaching powder, or potassium permagnate solution.
5) Distilled sea water is used for drinking purposes. For aeration of the distilled water it may be passed through a long column of wood charcoal; subsequently it is tasty and can be used for drinking purpose.