Water pollution is the contamination of water bodies (for example, lakes, rivers, oceans, aquifers and groundwater). This form of environmental degradation occurs when contaminants are discharged directly or indirectly into bodies of water without adequate treatment to eliminate harmful compounds. Water pollution affects the entire biosphere: plants and organisms that live in these bodies of water. In almost all cases, the effect is detrimental not only to the species and the individual population, but also to the natural biological communities.
Water pollution is an important global problem that requires an ongoing evaluation and review of water resources policy at all levels (international to aquifers and individual wells). It has been suggested that water pollution is the world's leading cause of death and disease, and that it represents the death of more than 14,000 people daily. It is estimated that 580 people in India die from diseases related to water pollution every day. About 90 percent of the water in China's cities is contaminated. As of 2007, half a billion Chinese people did not have access to drinking water. In addition to the serious problems of water pollution in developing countries, developed countries also continue to fight against pollution problems. For example, in the most recent national report on water quality in the United States, 44 percent of the miles of streams evaluated, 64 percent of the acres of lakes evaluated and 30 percent of the bays evaluated and Estuarine square miles were classified as contaminated. The head of China's national development agency said in 2007 that a quarter of the length of China's seven major rivers were so poisoned that water damaged the skin.