Abstract: 97 per cent of the total water on earth is saline with only 3 per cent available as fresh water. About 77 per cent of this fresh water is locked up in glaciers and permanent snow and 11 per cent is considered to occur at depths exceeding 800 meters below the ground, which cannot be extracted economically with the available technology. About 11 per cent of the resources are extractable ground water within 800 meter depth and about 1 per cent is available as surface water in lakes and rivers. Out of the 113,000 bcm of rain and snow received on the earth, evaporation losses account for about 72,000 bcm, leaving a balance of about 41,000 bcm, out of which about 9000-14000 bcm is considered utilisable.