Although not always the case, a pipe can serve as the single source discharging pollutants.

Point source pollutants come from a specific, identifiable location. Pollution from these types of pollutants is categorized as point source pollution by the U.S. Environmental Protection Agency. The Clean Water Act further defines point source pollution as a "conveyance … from which pollutants are or may be discharged." The term differentiates such pollutants from so-called non-point source pollutants -- water pollution without a specific source. Unlike point source pollution, non-point source pollution is caused by rainfall or snow melt, moving pollutants through and over the Earth's surface. An example would be agricultural runoff occurring over thousands of acres when excess rainwater washes agricultural chemicals into rivers and lakes. By contrast, point source pollution occurs when animal waste from a specific livestock farm in a given area enter a local body of water. Point source pollution is most commonly caused by three sources.

Waste-Water Treatment Plants

Heavy rainfall can overload waste-water treatment facilities, releasing point source pollutants.

Waste-water treatment plants are source pollutants because they release their effluent through a single source into waterways. Ideally, waste-water treatment plants reduce pollutants to levels that do not pose a threat to waterways. The material discharged from sewage-treatment plants is heavily regulated, but factors like heavy rainfall can overload treatment systems. This causes excess, untreated waste to enter local water sources, such as rivers and lakes. Under such circumstances, the pipes coming from plants are considered sources of point source pollution.


Factory smokestacks can emit carbon dioxide into the environment, a source of point source pollution.

Factories discharge pollutants through pipes and smokestacks, making them another point source. Waste-water pipes may lead to treatment plants or directly to waterways, and smokestacks can emit carbon dioxide and other pollutants into the air. Whether these pollutants are a danger depends on how well the factories treat their own waste, as well as the time of day, weather, and type of pollutant released.

Animal Agriculture

Large dairy farms often confine cows to facilities where waste can be managed, rather than to pasture.

Large farms raising cows, pigs and other livestock may also be point source pollutants. Such farms are known as confined animal-feeding operations (CAFOs). Like other sources of potential point source pollution, CAFOs must obtain a permit from the EPA to discharge waste. To receive a permit, CAFOs must have a plan for treatment of waste prior to discharge to reduce pollutants. However, untreated pollutants may enter the water from large farms due to a number of factors, including human error, break down of treatment process or overloading of the treatment system. This can result in degradation of water quality. In addition to obtaining the proper permits, CAFO operators can follow a number of practices to reduce potential for pollutants to enter nearby water sources. Large dairy operations, for example, often house animals on concrete rather than dirt, to allow farmers to collect and then store animal waste until it can be properly disposed of or incorporated back into the soil to provide nutrients for growing crops. Farmers may also lessen or eliminate point source pollution by moving waste water to a holding pond.

Controlling Point Source Pollutions

Because the source can be traced, point source pollution is more easily regulated.

Point source pollution has become less of a problem to the environment and human health because point sources are more heavily identified and regulated today than in the past. However, large volumes of rain, inadequate treatment, system failures and other circumstances can still make point source a potential danger to the environment and human health. Livestock operations are especially vulnerable to heavy rains, which can cause manure or feed stock to wash into waterways if not properly managed. Despite such risks, the EPA still identifies non-point source pollution as the greater danger to water quality because, unlike point source pollution, specific sources are not easily identified and regulated.