Water is the primary of source of living being. It is essential for survival. In present scenario, most of high tech people are polluting water for their own benefit. Their sense is so immoral that they are not in a position to look for better upcoming.

There are many ways by which water is polluted. The important sources of water pollution are: Domestic sewage (organic pollution), Biological and chemical oxygen demand, Industrial wastes (Industrial pollution).

Domestic sewage consists of human faeces, urine and the dirty used up water in houses. It contains a number of pathogenic bacteria and viruses. The sewage is released into the rivers. This causes the spreading of water borne diseases like dysentery, cholera, typhoid, malaria, etc.

Biological oxygen demand of sewage is defined as the amount of free oxygen required (in mg /s) for the bacterial break down of the organic matter under aerobic conditions at 20°C in a sample of water for a period of five days. It indicates the amount of decomposable organic matter in the sewage. Chemical oxygen demand is defined as the amount of oxygen (mg /L) consumed under specified conditions in the oxidation of organic and utilizable inorganic matter. It is a measure of both biologically utilizable and biologically inert matter, i.e. the total oxidizable impurities present in the sewage.

Industrial wastes (Hg, Cd, Pb, As, Zn, etc., petroleum, acids, alkalies, cyanides, chlorine) pollutants injure or kill fish and other aquatic life and also make water unfit for drinking. Compounds of metals like lead, arsenic and cadmium frequently act as water pollutants.

We all have to take immediate step to prevent water pollution.