Water pollution is the pollution of bodies of water, such as lakes, rivers, seas, the oceans, as well as groundwater.  It occurs when pollutants reach these bodies of water, without treatment. Waste from homes, factories and other buildings get into the water bodies and as a result water gets contaminated.
Water pollution is a problem for the species and ecosystems there. It affects plants and organisms living in the water. In almost all cases the effect is damaging not only to individual species and populations, but also to the wider biological communities. The color is usually green or brown but normal water can be blue.
Agriculture is one of the major sources of water pollution. The fertilizers given to the crops for better growth are washed into rivers and lakes, which in turn pollutes the water.
There are many chemicals that are naturally found in these bodies of water. Today water may be polluted by nitrates, phosphates, oil, acid rain, and debris such as sediment, fallen logs and so on. When people and animals drink water from such rivers, the poisonous chemicals may affect them. Life in rivers are also affected, and humans who consume fish may also have health problems.