Water pollution is the contamination of water bodies like lakes, rivers, ground water and oceans. It occurs due to the discharge of untreated pollutants into water bodies. It not only affects plants and organisms living near the location of discharge but also travels to other locations through transportation of polluted water.
Various sources of water pollution are:
Factories and industries which release various toxins, untreated effluents and heavy metals and industrial solvents into natural water bodies.
Agricultural farms releases fertilizers and pesticides which leads to eutrophication and biomagnification.
Mining exposes heavy metals and sulphur which were buried deep in the earth into water bodies.
Sewage pipe and storm water drains release various pathogens, disinfectants and detergents.
Air pollution releases pollutants like sulphur dioxide, oxides of nitrogen which are washed down by rains.
Food processing units and their waste includes fats and greases.
Based on their origin, sources of water pollution are generally grouped into two categories:
Point source pollution refers to contaminants that enter a water body from a single identifiable source such as a pipe or a ditch.
Non-point source pollution refers to diffused contamination that does not originate from a single discrete source but is the cumulative effect of contaminants gathered from a large area such as leaching of fertilizers and pesticides from agricultural land.