Water pollution is the contamination of water by sewage, toxic chemicals, metals, oils, or other substances. It can affect such surface waters as rivers, lakes, and oceans, as well as the water beneath the earth's surface, called ground water. Water pollution can harm many species of plants and animals.

Causes of water pollution: Water pollution occurs when people put so much waste into a water system, which is natural, causing cleansing processes cannot function properly. It includes sewage, industrial chemicals, agricultural chemicals, and livestock wastes. Another form of water pollution is the clean but heated water discharged by power plants into waterways. This heated water, called thermal pollution, harms fish and aquatic plants by reducing the amount of oxygen in the water. Chemical and oil spills can also cause devastating water pollution that kills water birds, shellfish, and other wildlife. Some water pollution occurs when there is improper separation of sewer wastewater from clean drinking water. In areas that lack modern sewage treatment plants, water carrying human waste can flow into drinking water supplies. Bodies of water support a natural cycle of life processes. When the oxygen supply in the water becomes too small, fish and other water animals die. Water pollution has become a serious problem in most countries, particularly Canada, China, India, Japan, Russia, and the United States

A healthy water system (see picture)

How water pollution occurs (see picture)

Example of water pollution (see pictures)

Chemical wastes from industries dumped into the sea

Polluted Beaches