What is the purpose of a septic tank?

The purpose of a septic tank is to facilitate the separation and anaerobic decomposition of wastewater solids. When wastewater enters the tank, it is held for a period of time, allowing heavier solids to settle at the bottom to form sludge, while lighter materials such as oils and grease rise to the top to form scum. This separation process is essential for the proper functioning of the septic system, as it allows for the treatment of solids in an anaerobic environment, which helps break them down over time.

Additionally, this anaerobic decomposition process is crucial because it prevents the solids from moving into the drain field, thereby maintaining the efficacy of the wastewater treatment system. The design and function of a septic tank are critical for ensuring that only partially treated liquid effluent leaves the tank and is distributed to the absorption field, where further treatment occurs in the soil.