The sources of water pollution can be divided into two types. These are:
1. Point sources of water pollution
2. Non-point sources of water pollution
Point Sources of Water Pollution
These are those sources of water pollution which have a specific fixed location. Examples of point sources of water pollution are factories, power plants, oil wells and coal mines.
Non-Point Sources of Water Pollution
These are those sources of water pollution which do not have a specific fixed location. Examples of non-point sources of water pollution are rain water from streets and roads, flow of fertilizers rich water from fields, gardens and lawns, flow of dirty water from construction sites.
Major Sources of Water Pollution
The major sources of water pollution are:
1. Domestic Sewage
When domestic sewage containing dirt, oils, human excreta, detergents, paper and dissolved inorganic compounds is added into water sources, the whole water is polluted and becomes unfit for use.
2. Industrial Wastes
The wastes produced by industries contains many toxic chemicals such as mercury, lead, arsenic, acids, alkalies etc. when industrial wastes are added into water sources, they pollute the water.
3. Chemical Fertilizers and Synthetic Detergents
Excessive use of fertilizers and synthetic detergents also cause water pollution. Most of fertilizers and synthetic detergents are non-biodegradable and contain phosphate salts. When fertilizers and synthetic detergents rich water flow in the rivers and lakes, the phosphate salts present in them cause rapid growth of algae in water. When algae die, their bodies are broken down by bacteria. This process uses up oxygen in water bodies. This leads to reduction of oxygen in water and cause death of aquatic animals like fishes. This process is also known as eutrophication.
4. Oil
Leakage of oil into sea during its extraction from oil wells or accidents of ships during transportation of oil also cause water pollution.
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