Onsite Wastewater Treatment / Septic


Septic systems are used to treat and dispose of small volumes of wastewater onsite, usually from houses and businesses located in suburban and rural locations not served by a centralized public sewer system. Septic systems treat wastewater from household plumbing fixtures (toilet, shower, laundry, etc.) through both natural and technological processes.

Septic systems are also called:

  • onsite wastewater treatment systems,
  • decentralized wastewater treatment systems,
  • cluster systems,
  • package plants,
  • on-lot systems,
  • individual sewage disposal systems, and
  • private sewage systems.

Onsite wastewater treatment systems (septic systems) have the potential to contaminate groundwater and surface water resources, including drinking water supplies, with nitrates and other nutrients, chemicals, pathogens, and pharmaceuticals. However, when properly located, designed, constructed, and maintained, septic systems provide an effective and efficient means of treating domestic sewage and protecting water quality. Furthermore, there are economic and ecological advantages to managing wastewater within the watershed where it is produced.

Thousands of unsewered communities and rural residences will continue to depend on onsite systems for wastewater treatment and disposal. Today, as the population migrates farther from metropolitan areas, about one-third of all new development is served by decentralized treatment systems (USEPA, 2004). Onsite systems allow communities to develop while providing them with the means for adequately handling wastewater. To minimize the impacts of these systems on ground water, we need to:

  • Ensure that onsite systems are properly designed, installed, and maintained.
  • Take full advantage of innovative designs and sound science.
  • Adopt effective management solutions.
  • Actively educate the public on what wastes should not be put into their systems, and how these systems should be maintained.

From the Ground Water Report to the Nation

Onsite Wastewater Treatment Systems – Summary Sheet : Full Chapter