Water Pollution:

Definition:
“The presence of undesirable substances into fresh and natural water which cause harmful diseases in human beings as well as aquatic life is called water pollution.”

Types Of Water Pollution:
Following are the major types of water pollution.
i) Sea-water Pollution
ii) River water Pollution
iii) Land Water Pollution

Causes Of Water Pollution:

1) Pollution Through Domestic Activities:
Domestic activities pollute the water when following kinds of wastes are added.
i) Soap and detergents
ii) Chemicals used in the houses
iii) Waste from slaughter house
iv) Waste from hospitals
v) Waste from bakeries
vi) Human and animal faeces
vii) Waste food

2) Pollution Through Industrial Activities:
Industrial sector is a great source of pollution of water and air. Many industrial units produce waste materials in the shape of solids, liquids and gases. The industrial wastes are.
i) Poisonous gases
ii) Acids, bases and harmful salts
iii) Pesticides and plastics
iv) Radioactive wastes
v) Toxic wastes from fertilizer factories
vi) Wastes from chemical factories

Water Pollution In Pakistan:
In Pakistan people do not take pain to dispose the waste materials in a proper way. Instead of dumping wastes in the drums and places meant for them they freely throw these into the water drains.

Water pollution is very prominent and widespread as a result of urban and industrial activity. Sewage waste from cities and industrial waste are the main factors of water pollution. Many other kinds of wastes which pollute water are from agricultural lands which contain pesticides, waste foods, fertilizers and animal excreta. Wastes from power plants contain radioactive materials, hot water and minerals which also pollute the water. Soaps, detergents, human excreta, animal faeces, wastes from slaughter houses, disease causing micro-organisms from patients and chemicals etc. are drained into water which causes massive water pollution.

Two Important Industries Of Pakistan Causing Water Pollution:
1) One of the biggest sources of water pollution is the tanning and leather industry. The industry uses toxic chromium metal and many other toxic substances/chemicals. These toxins are released in natural waters. Effluent of this industry has polluted ground water and water of nearby rivers. This industry is frequent in Kasur and Sialkot area.

2) Pesticide industry in Kala Shah Kaku near Lahore releases huge quantity of acids, pesticides and other dangerous wastes. These wastes are getting entry into a stream flowing nearby. The water of the stream is dangerously polluted. This water ultimately goes to the rivers.

Effects:
i) Bacteria, viruses, protozoa and worms are carried in polluted water. The diseases caused by them are as under:
a) Bacteria: Typhoid, cholera, Dysentery, enteritis.
b) Viruses: Hepatitis, Polio, Viral enteritis.
c) Protozoa: Amoebic dysentery, diarrhoea.
d) Parasitic worms: Schistostomiasis
ii) It causes death of aquatic animals.
iii) It decreases the fertility of the soil and results in low production.

Methods To Control Water Pollution:
Different methods can be used to control water pollution.
i) The whole sewage waste should be dumped after any treatment.
ii) Sewage treatment plants should be installed in cities.
iii) The sewage waste must not be drained in river to save water from pollution.
iv) Industrial waste should be treated before reaching natural water.
v) Industries should be established away from cities and rivers.
vi) Nuclear dumping in oceans should be banned.
vii) Modern scientific methods should be used in agriculture.