What are the main functions of a septic tank?

The primary function of a septic tank is not only to store wastewater but also to remove solids and provide treated effluent for further processing in the drain field. Septic tanks are designed to allow wastewater from homes to flow into them, where gravity helps separate solid waste from liquids. The solids settle at the bottom of the tank, forming a sludge layer, while lighter materials, such as oils and grease, float to the top, creating a scum layer.

The anaerobic bacteria within the septic tank play a crucial role in breaking down the organic matter in the wastewater. This breakdown results in a partially treated liquid effluent, which is then discharged into the drain field for further treatment through soil filtration and microbial action. The effective removal of solids and the treatment of wastewater in the septic tank is essential to prevent pollution and to protect groundwater and surface water from harmful contaminants.

Other options do not fully encompass the functions of a septic tank. For instance, while storing wastewater is a part of the tank's function, it is not the sole purpose. Chemical treatment is not the primary mechanism employed in septic tanks; instead, they rely on biological processes for treatment. Additionally, septic tanks do not control groundwater levels; their primary focus is on treating and managing wastewater.