Where does water pollution come from?
Water pollution is difficult to trace to a specific discharge point. Because it comes from many diverse sources, it is hard to control. Examples of common pollutants include fertilizers, pesticides, pet wastes, sediments, oils, salts, trace metals and litter. They come from farms, yards, roofs, construction sites, automobiles, and streets.
Water pollution is usually caused by human activities. Different human sources add to the pollution of water. There are two sorts of sources, point and nonpoint sources. Point sources discharge pollutants at specific locations through pipelines or sewers into the surface water. Nonpoint sources are sources that cannot be traced to a single site of discharge. Examples of point sources are: factories, sewage treatment plants, underground mines, oil wells, oil tankers and agriculture. Examples of nonpoint sources are: acid deposition from the air, traffic, pollutants that are spread through rivers and pollutants that enter the water through groundwater. Nonpoint pollution is hard to control because the perpetrators cannot be traced.
