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ENVIRONMENTAL HEALTH CONCERNS AND TOXIC CHEMICALS WHERE YOU LIVE, WORK, AND PLAY

Wastewater Treatment/ Wastewater

About

Wastewater is used water from homes, businesses, hospitals, and industries. Wastewater carries everything that is flushed or goes down the drain. Extensive networks of underground pipes channel wastewater from homes and businesses in cities and suburbs to regional treatment facilities.

Wastewater treatment facilities clean wastewater by removing pollutants before the remaining water is discharged into the environment. In some regions, urban and industrial runoff collected by stormwater systems is also piped to treatment facilities.

See also: Methane

What is it?

A cesspool is an outdoor, underground drywell that receives waste and wastewater from homes, industries, or businesses. A cesspool may also be called a shallow disposal system or Class V Well. After waste enters the well, it breaks down into liquids that seep through holes into the ground.

Why is it a concern?

Cesspools are not designed to treat sanitary waste. Untreated waste from cesspools can enter groundwater and contaminate drinking water, exposing people to harmful bacteria and viruses. Similarly, if toxic liquids like oil, gasoline, pesticides, or paints enter groundwater through a cesspool, they can harm people. (These liquids should never be poured down the drain.) Foul odors from failing cesspools can be nauseating. Flies and mosquitoes that can spread disease may breed in wet areas where wastewater reaches the surface.

Cesspool systems should be properly located, constructed, and operated to protect human health and prevent contamination. State and local governments regulate cesspools for homes. The U.S. Environmental Protection Agency (EPA) banned large-capacity cesspools in April 2005. (The definition of “large-capacity” may vary from state to state.) Many are being replaced with modern septic systems.

What pollutants are of greatest concern and who is at risk?

Cesspool wastewater often has higher levels of nitrates and coliform bacteria than are allowed in drinking water. Nitrates pose a significant threat to the health of infants. When ingested, nitrates can interfere with the blood’s ability to carry oxygen.

The wastewater may contain other pollutants such as phosphates, chlorides, grease, viruses, and chemicals used to clean cesspools.

People who use well water or who live or work near where wastewater has reached the surface are at risk for harm from contamination.

National Library of Medicine Resources and Databases

What is it?

A septic system is used to treat and dispose of wastewater, usually from homes, businesses, and commercial buildings that are close together. Septic systems are widely used in rural and other areas where homes do not have access to a local wastewater treatment facility.

A typical septic system includes a pipe from a home’s or building’s plumbing system; a septic tank, where bacteria digest organic matter and solids separate from the wastewater; a drain field or leach field; and soil. Wastewater liquid flows from the tank to pipes buried in the drain field. The soil in the drain field filters the water, and then the soil surrounding the drain field filters the water again. Solids remain in the tank and are regularly pumped out by septic system maintenance companies.

Why is it a concern?

A failing septic system can contaminate groundwater and sources of drinking water with untreated sewage, exposing people to harmful bacteria and viruses. Similarly, if toxic liquids like oil, gasoline, pesticides, or paints enter groundwater through a septic system, they can harm people. (These liquids should never be poured down the drain.) Foul odors from failing septic systems can be nauseating. Flies and mosquitoes that can spread disease may breed in wet areas where wastewater reaches the surface.

What pollutants are of greatest concern and who is at risk?

Wastewater can include nitrogen, phosphorus, bacteria, and viruses. People who use well water or who live or work near where wastewater has reached the surface are at risk for harm from contamination.

National Library of Medicine Resources and Databases

Additional Resources

What is it?

A sewer is a channel that carries stormwater runoff and wastewater from the source to a treatment plant or receiving stream. Storm sewers carry runoff from rain or snow. Sanitary sewers carry household, industrial, and commercial waste. Combined sewers handle both.

Why is it a concern?

Sanitary sewer overflows can release untreated sewage into basements, streets, or streams before they can reach a treatment facility. Because sanitary sewer overflows contain raw sewage, they can carry bacteria, viruses, parasites, intestinal worms, and molds. The diseases they may cause range from mild stomach cramps to life-threatening illnesses such as cholera, infectious hepatitis, and severe gastroenteritis.

What pollutants are of greatest concern and who is at risk?

Wastewater can include nitrogen, phosphorus, bacteria, and viruses. People who use well water or who live or work near where wastewater has reached the surface are at risk for harm from contamination.

What is it?

A wastewater treatment facility cleans wastewater in two stages. In the first stage, solids are allowed to settle and are then removed from wastewater. In the second stage, biological processes further clean the wastewater. Chlorine then removes the remaining bacteria.

Why is it a concern?

Wastewater can include human and animal waste, food scraps, oil, pesticides, fertilizers, heavy metals, and chemicals. It can include bacteria, funguses, parasites, and viruses. Well-managed, effective wastewater treatment facilities remove these contaminants and are essential to good public health. Untreated wastewater can contaminate drinking water and spread disease. It can also create toxic gases and odors.

Treatment facilities are usually located next to a natural waterway. After treatment, the water is discharged into a nearby river or ocean. Treated water may have high levels of phosphorus and nitrogen which can feed algae blooms. Some wastewater treatment facilities take the extra step of reducing phosphorus and nitrogen before returning the treated water to the environment.

What pollutants are of greatest concern and who is at risk?

Workers at a wastewater treatment plant can be exposed to chlorine or other gases. They may also be exposed to pollutants in the wastewater that can spread disease and infection.

National Library of Medicine Resources and Databases

Additional Resources

Reduce your risk

  • Do you use well water?
  • Do you live or work near wet areas where wastewater has reached the surface?
  • Do you live near or work at a wastewater treatment facility?
  • Children should avoid playing near wastewater treatment facilities.
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