Water can be obtained from a variety of natural sources. The criteria to be satisfied by water sources are:
1. The quality of water must be acceptable
2. Quantity must be sufficient to meet the demand.
CLASSIFICATION OF WATER SOURCES
1. Above the surface : Rain
2. Surface water Reservoirs, rivers, streams,
ponds, tanks and lakes.
3. Ground Water Shallow wells, deep wells and springs.
Rain is the most important source of water. It is the purest water free from pathogenic agents. It is clear, bright, sparkling and soft. Because it is soft, it has a corrosive action on lead pipes. Impurities: Suspended impurities like dust, soot, micro - organisms; gases like carbon dioxide, nitrogen and ammonia. These are picked up by rain water from the atmosphere.
The sources of surface water are i) Reservoirs ii) Rivers and streams iii) Tanks, ponds and lakes.
These are artificial lakes constructed by masonry or dams built across rivers. Water from reservoirs is clear, palatable, soft and free from pathogenic organisms. But it may be contaminated by human habitations or animals.
Rivers satisfy water needs of several cities and villages. It contains impurities produced by sewage, industrial wastes, human and animal washings etc. So it is not suitable for dunking without treatment.
Tanks: They are large excavations in which water is stored. They form an important source of water in many of the Indian villages. They are contaminated by silt, colloidal matter, aquatic vegetation, washings of humans and cattle. Also the regular defecation around the edges may be drained into them by rain. Because of high degree of contamination, tank water is not suitable for drinking. Tanks can be improved by:
1. Raising the edges and fencing them.
2. By constructing an elevated platform from where water can be drawn.
3. Periodical removal of weeds.
4. Regular cleaning at the end of dry season.
It is obtained from wells or springs. It is naturally filtered though the ground.
1. It is free from pathogenic agents
2. It does not require treatment
3. Supply may be adequate
1. High content of minerals like calcium and magnesium which make it hard.
2. Requires lifting by pumps or other physical means.
They are the main sources of water in many Indian villages and towns. According to the method of construction, they are classified as dug wells and tube wells.
It is the commonest type in India.lt may be an unlined ketch well or a puck well lined by bricks or stones. If the puck well contains steps (to enable people to get into it to fetch water) it is called step well. Step well may be contaminated if people take bath, or wash the face, hands and feet. Also guinea worm disease may be contacted from step wells.
It is an improved ideal dug well with the following features:
1. It is located at an elevated site at least 50 feet away from a source of contamination like latrine, bathing place, cattle shed etc.
2. It should have a lining built by bricks or stones such that water does not enter from the sides.
3. It should have a parapet, platform, drain and covering.
4. It should have a hand pump to draw water in a sanitary manner.
5. The quality must conform to the standard of safe and wholesome water.
There are two types of tube wells. Shallow tube wells and deep tube wells.
Shallow tube well (or driven well) consists of an iron pipe sunk into the water bearing stratum. It has a strainer at the bottom and hand pump at the top. It can be prevented from pollution by
i. Locating it 15 meters away from a source of pollution like latrine or cattle shed.
ii. Providing a concrete platform all around.
Deep tube wells are several hundred feet deep. They are drilled by mechanical equipment's. Water is drawn from them by electrical
motor. These wells are costly to construct. But they are ideal since they supply pure water for long years.
Springs are natural outlets of ground water held under pressure in the ground. There are four kinds of springs-shallow springs, deep springs, mineral springs and thermal springs. Spring water may vary in quality and the yield is also very low.