Water is our most abundant resource and covers about 71% of the earth's surface. About 97% of the earth's total water is ocean water and is too salty for drinking, irrigalion and most industrial purposes. Cut of the remaining, more than three-fourths is unable for use because it lies too far under the earth's surface or is locked up in glacier, polar ice caps etc. Ultimately, only abcut 0.003% of the world's water supply is available as fresh water for human use. This supply is also unevenly distributed. Human beings have corrected these imbalances with varying degrees of success by. capturing water in reservoirs behind dams, transferring water in rivers and streams from one area to a different, tapping underground supplies, and attempting to scale back water use, waste and contamination. With the growth of human population, there is an increasing need for large amounts of water to fulfil everyone's needs One of the greatest challenges facing the world is the management of water resources. Water sources are overused or wasted to such an extent that they locally run dry. Water sources are also becoming heavily polluted by sewage and toxic substances that it becomes impossible to use this water. The mismanagement of water resources has resulted in inequitable distribution of water. Some use more water than they need while others do not have access to clean water to all In short, water resource management is the process of managing both the quantity and quality of the water usedd for human benefit without destroying its availability and purity.
SOURCES OF WATER FOR SMALL COMMUNITIES AREAS
Since most of the Indian rivers are non-perennial with meagre storages, and nural villages are generally located at far off distances from these rivers, it has generally not been feasible to supply surface waters to the seattered and isolated rural areas. Most af our villages depend upon ground water supplies, to be extracted through wells and tubeuells. In hilly regions sometimes, natural springs are available in exceptional cases. The degree and type of treatment to be given depend upon the quality of water source available. Various water sources available in rural areas are: 1. Rivers and Streams: Generally, the waters of rivers and streams are soft, containing relatively low concentrations of dissolved salts. They are often affected by pollution in small streams near settlements. The quality of the water can vary considerably with rainfall, but turbidity can be expected at most times. Slow flowing rivers can contain considerable amounts of organic matter. 2. Lakes: Large lakes, in general, have the water quality as fairly good and consistent Near the areas of industrial and agricultural development, and sewage and industrial efluent discharges may affect the water to such an extent that it becomes impracticable to consider it as a source for public water supply. 3. Springs and Boreholes: Springs are natural sources of ground water, while the boreholes are dug or drilled to lift ground water. These sources can provide reliable water supply. Moreover, if properly maintained and kept sufficiently away from pit privies and soakpits, they can provide us water aimost free from pollution. Proper protection of the site of spring from defecation and drainage is very important to avoid its contamination. Such a source can be utilised to provide supply to a community without pumping, at minimum cost and maintenance. A well or a bore hole is dugged or drilled into the permeable strata, and the water lifted manually or by mechanical pumps. It is usually advisable to prevent surtace water entering the well by sealing the top section with brick or concrete, as shown in Figs. 10.1 and 102 for dug well and driven tube well respectively.
. Underground Storage Tanks: Underground storage tanks or tanks at ground level are required to collect water from municipal supply lines, if the water pressure in the main is insufficient to reach the overhead tank. The water is then pumped up to the overhead tanks. Direct use of pumps on the municipal mains is prohibited by the municipal authorities, as it reduces the water pressure in the adjoining houses or buildings. Such a tank is made of R.C.C or brick masonry, and has to be structurally designed safe to withstand earth pressure (when the tank is empty). The tank is to be filled from the municipal supply inlet, and is covered trom the top to avoid any contamination. The top cover may be provided with a manhole for inspection and cleaning purposes. Suitable pump is installed to tift the water from this tank and up to the overhead tank. Care should be taken to construct an underground tank so thats () It is water-Tight and does not leak when empty or full: (ii) It is not located in low-lying areas, which may permit entry of surface water from the top: (i) It should prevent ingress of subsoil water into the tank through leakage; (iv) It should not be located near sewers, septic tanks, soak pits, oil tanks, or under- ground car parking areas, to avoid seepage of polluted surface waters; (r) The overflow water level in the tank should be above the surrounding ground level, to prevent the surface water from entering the tank through overflows; (vi) The masonry or R.C.C. retaining walls of the tank should be structurally safe to withstand the earth pressure from behind, when the tank is empty. General Requirements of Domestic Storage Tanks
1. It should be water tight.
2. It should be constructed with non-corrosive and non-toxic materials.
3. These should be provided with vent pipe for ventilation and preventing pressures when water is withdrawn.
4. These should have overflow pipe along with ball valve with flsat.
5. These should have a scour pipe with a plug at the bottom for emptying the tank.
6, These should have manhole with cover on the roof of the tank to prevent entry of dust mosquitoes etc.