Sources of Water Pollution

Sources of Water Pollution: Water is the most essential for all living beings, both plants and animals. It covers nearly three-fourths of earth’s surface in the form of snow over mountains, as a liquid in oceans, a rivers and ponds. Since it is primarily used for drinking, the quality of drinking water is a very vital factor. There are many sources of pollution which cause the actual problem.

What is Water Pollution Definition?

The change in the normal properties of water (physical, chemical and biological) by the presence of foreign materials.

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Sources of Water Pollution

Water pollution can be caused in a number of ways:

Organic Pollutants.

The list of organic pollutants is very large. It includes manures wastes from food processing, rags, paper discards, decaying plants etc. and other organic wastes. All of them cause pollution of water.  These are decomposed by aerobic bacteria into carbon dioxide, nitrates, sulfates phosphates etc.But they take up dissolved oxygen from water.  As a result, the oxygen contents in water decrease considerably. This causes the death of aquatic animals particularly the fish.

It may be noted that anaerobic bacteria do not need oxygen from the decomposition of the organic matter. However, some toxic gases like hydrogen sulfide, ammonia, phosphine, methane etc. are produced. These are quite often noticed in the sewage wastes.

Industrial wastes.

The compounds of lead, mercury, cadmium, nickel, cobalt, zinc etc. which are the products of chemical reactions. These are carried in the industrial units also pollute water to a large extent and are responsible for many diseases. Mercury leads to Minamata disease, and lead poisoning leads to various types of deformities. In addition to this, these chemical substances become a part of the soil. They harmfully affect the plant growth and soil biota. Both groundwater and water bodies are polluted due to the chemical reactions are known leaching.


These are the chemical substances which are added to the soil to provide the essential minerals containing N, P, S etc. The common fertilizers are calcium ammonium nitrate, urea, triple superphosphate, potassium sulfate, potassium nitrate etc. However certain part of these fertilizers react with water chemically (known as leaching) and pollute the underground water. When this water is used for drinking purposes containing potassium nitrate, in particular, it harms the respiratory system. Moreover, the presence of extra minerals in water is also harmful to many crops. 

Sources of Water Pollution

Pollution of water by acids

Acid polluted water is very harmful to the life. Acid Rainwater containing a high proportion of the acid.This mixes with seawater and pollutes it. In addition, the industrial wastes particularity iron pyrites (FeS2) are slowly converted into sulphuric acid.As a result of series of reactions and increase the acidity of water.


These include insecticides, fungicides, herbicides, rodenticides, etc. These mostly chemically chlorinated hydrocarbons, organophosphates, metallic salts etc. Common pesticides are D.D.T. aldrin, B.H.C., heptachlor etc. These are quite useful since they boost the agriculture yield by protecting the crops from pests. But the use of pest has very harmful effects. They dissolve in water to a small extent and pollute it. Since all the pesticides are toxic in nature, they are injurious to both plants and animals. The frequent use of pesticides without proper control and choice can lead to deformities in fetus, nervous system, stomach cancer, darkened skin and can also cause damage to eyes.The excess use of pesticides has resulted in defoliation of forests.

Ways to Prevent Water Pollution

We have seen that the two major sources of water pollution are: sewage and industrial. They should be removed before it is put to use.

Treatment of Sewage

Following measures must be taken to check pollution by sewage.

(i) Sewage must be churned by machines so that the large pieces may break into small and may get mixed thoroughly. The churned sewage is passed into a tank with a slope. Heavier particles settle and the water flowing down is relatively pure.

(ii) Water must be sterilized with the help of chlorination. It kills microbes of sewage fungus as well as some pathogens, spores or cytes. Chlorination is very essential, particularly in rainy season.

(iii) Treatment with alum, lime etc. also helps in its purification.

Treatment of industrial waste

The treatment of industrial waste depends upon the pollutants present. In order to ascertain it, the pH of the medium is first determined and the then neutralized with the help of suitable acids or alkalies. The chemical substances present in the industrial waste products dissolved in water can be precipitated by the suitable chemical reaction and removed later. Quite recently, photocatalysis and ion-exchangers have been for the treatment of industrial wastes.

Water has also unique property. It has the property to dissolve a large number of compounds both organic as well as inorganic. Moreover, it remains as a liquid over a wide range of temperature from 0-100°C. It is, quite often, regarded as the universal solvent. This property is the major cause of pollution since the salts and organic matter dissolves in water and contaminates it.


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