“Water pollution is defined as presence of any foreign substance or energy in water in such concentration and for such duration that tends to degrade the quality of water so that man, animal or any other organisms cannot enjoy the beneficial qualities of water but the use constitute a hazard.” Water pollution is classified as freshwater pollution (it includes both surface and ground water pollution) and marine water pollution.
Main Sources of Water Pollution
When the cause and place of pollution is easily identifiable, it is known as Point source of water pollution Example Municipal and industrial discharge pipes.
When the cause and place of pollution cannot be readily identified, it Is known as non-point source of water pollution Example Mining runoff and acid rain Water Pollutants
(i) Organic Pollutants
They include oil, synthetic organic compounds, sewage and agricultural run-off, disease-causing wastes and oxygen-demanding wastes.
(ii) Inorganic Pollutants
They include metals, metal compounds, organometallic compounds, mineral acids, inorganic salts, etc.
(iii) Suspended Solids and Sediments
They comprise of sand, silt and minerals eroded from the land.
(iv) Radioactive Materials
They include radioactive isotopes from nuclear reactors, nuclear power plants, research, industrial applications, agriculture and therapeutic as well as diagnostic medical applications.
(v) Thermal Pollution
They include discharge of waste heat to water body by thermal and nuclear power plants.