Water pollution is due to contamination of water by pollutants and alterations in the physical, chemical and biological properties of water which shows effects on humans.
Pollution of water is due to the discharge of chemicals or wastes into the system from industries without any treatment. Drinking of polluted water leads to health diseases and some times leads to death. Here are some causes for water pollution.
One of the major causes of water pollution is due to industries. Industries dump their wastes into rivers and oceans without any treatment. These wastes include heavy metals and toxic products such as arsenic, lead and mercury which causes harm to environment.
Another major cause that leads to pollution of water is sewage waste. This pollution is due to the improper sewage treatment. Sewage contains faeces, urine and chemical wastes released by human. These faeces contains microbes such as coliform bacteria. If we drink such polluted water it causes diarrhea, nausea, vomiting and gastric irritation.
Now a days, use of vehicles is increased which is polluting air and water. These vehicle release toxic fumes such as carbon monoxide, sulfates and nitrates. These come in contact with water vapor present in the air and gives mild corrosive acids. This acids reaches ground as acid rains. Consumption of polluted water leads to diseases in humans.
Burning of coal
Burning of coal leads to release of mercury into the atmosphere. This mercury enters earth and reaches to the rivers and lakes. Thereby ground water gets polluted. Drinking water polluted with this leads to lung and kidney problems and increases the risk of cancer.
As the world is more dependent on nuclear energy, the wastes from nuclear industry plays major role in water pollution. Wastes from nuclear industry, medical and scientific research centers includes radio active substances and toxic metals released into the lakes and rivers without any treatment. Thereby water gets polluted. Drinking such water leads to genetic disorders.
Oil spills is one of the major causes for water pollution. Large oil tank ships release gallons of oil as wastes into the oceans.
Pesticides and fertilizers used in agricultural farming containing nitrogen and phosphorus enrich the soil near the lakes and rivers and makes the algae to grow. It utilizes all the oxygen, and water becomes polluted which leads to diseases.
Underground storage and leakage
Many petroleum and oils are stored in metal pipes and sewage pipes underground. Over a period of time, the pipes rust and leakage from these enters into the ground and reaches water system. There by water gets polluted.