Water is indispensable and one of the precious natural resources of this planet. Water is the most essential commodity for human consumption and it is one of the renewable resources which must be prevented from deterioration in quality. Its quality plays an important role in the overall water balance in the environment. About 70 per cent of the planet is covered with ocean, and the average depth of the ocean is several thousand meters. More than 97 per cent of the Earth's water is saline and therefore is unusable for drinking purpose because of the salt. About 2 per cent of the planet's water...