On an average a human being consumes about 2 litres of water every day. Water accounts for about 70% of the weight of a human body. About 80% of the earth surface is covered by water. Out of the estimated 1,011 million Km3 of the total water present on earth, only 33,400 m3 of water is available for drinking, agriculture, industrial and domestic consumption. Rest of the water is locked up in oceans and polar ice-caps and glaciers. Considerable part of this limited quantity of water is polluted by sewage, industrial waste and a wide array of synthetic chemicals. Various types of water pollutants are responsible for the pollution of water such as, organic pollutants including- oxygen demanding waste, disease causing waste, synthetic organic compounds, sewage and agricultural runoff, oil ; the inorganic pollutants including various metals and metallic compounds, suspended solids and sediments, radioactive materials etc. Water pollution is indicated by various water quality parameters such as- colour, odour, DO (Dissolve Oxygen), COD (Chemical Oxygen Demand), BOD (Biochemical Oxygen Demand), pH, temperature range, turbidity, acidity, alkalinity etc. There are many environmental effects due to water pollution.
The water-borne diseases are still a source of worry, particularly in under developed and developing countries. The quality as well as the quantity of clean water is of vital significance to the welfare of mankind.