Water is a precondition of life. Besides various uses of water, it is mainly used in irrigation as India is an agricultural country. Water is a renewable resource. Life is impossible without water. Its uses are limitless whether it is in home or in fields or in industries. We get water mainly from rain, rivers, wells, ponds and lakes. Sea-water is almost useless for domestic or industrial purposes. India is said to be a Monsoon country. But the distribution of Monsoon rainfall is uneven both regionally and seasonally. Moreover, it is not dependable as its occurrence is not at stipulated times. River is the main source of surface water. The mean annual flow of the Indian rivers is estimated to be about 1,869 billion cubic metres (bcm). About 690 billion cubic metres or 36.92 percent of it is available for use. On the basis of hydrology, Indian rivers are divided into: Himalayan rivers and Peninsular rivers. Himalayan rivers have their resources in the glaciers and snow fields, so they are perennial in nature. Peninsular rivers depend on monsoon rains, so they are seasonal.