What is the purpose of a septic tank?

The purpose of a septic tank is to separate solids from liquids and begin the treatment of wastewater. This process is fundamental to how septic systems operate. In a typical septic tank, wastewater from a residence flows in and is allowed to settle. The heavier solids sink to the bottom to form sludge, while lighter materials, like fats and grease, rise to the top as scum.

As the wastewater sits in the tank, anaerobic bacteria break down some of the organic matter, initiating the treatment process before the effluent is sent to a drain field for further treatment and filtration into the soil. This separation and initial treatment are essential for managing domestic wastewater safely and effectively, preventing contamination of groundwater and the surrounding environment.

The other options do not align with the primary function of a septic tank. Storing drinking water, filtering and recycling used water, or holding stormwater runoff are functions not related to the operation and purpose of septic tanks. Thus, understanding this core function is crucial for anyone involved in septic system installation and maintenance.