What is the primary purpose of a septic tank?

The primary purpose of a septic tank is to treat and store wastewater. Septic tanks are essential components of a decentralized wastewater treatment system commonly used in areas that lack access to centralized sewer systems. When wastewater from households flows into the septic tank, it undergoes several processes.

Inside the tank, solid waste settles at the bottom, forming sludge, while lighter materials like grease and oil float to the surface, creating a scum layer. The tank is designed to allow the liquid portion, known as effluent, to flow out into a drain field or leach field, where it is further treated by the soil and filtered before re-entering the groundwater. This natural process minimizes the environmental impact of wastewater and helps maintain sanitary conditions.

The other options do not accurately describe the primary role of a septic tank. For example, while septic tanks do play a role in wastewater management, they do not provide water for irrigation or act as a backup water supply. Although improved soil quality can result from the treated effluent, this is more of a secondary benefit rather than the central function of the septic tank system itself.