Due to reasons such as increasing urbanization, industrial expansion and intensified agriculture, water is frequently used heedlessly for dilution and transport of wastes, beyond an economically and socially sensible level. Also, the volume of waste water is continuously increasing. Water is used as a coolant for power stations and other industrial processes, thereby causing thermal pollution of receiving waters and disturbance of their natural ecology. Any act of pollution immediately or eventually involves the hydrolic cycle of the earth and results in deterioration of water quality, because even pollutants emitted into the air and those present in the soil are washed out by precipitation.