What is the purpose of a septic tank?

The purpose of a septic tank is to separate solids from liquids and initiate the treatment process of wastewater. When household waste enters the septic tank, it first settles into layers: heavier solids sink to the bottom, forming sludge, while lighter materials, such as oils and grease, float to the top, creating a scum layer. This separation is crucial as it allows the liquid effluent to be directed to the drain field or leach field, where further treatment and eventual absorption into the soil occur.

This initial step in the treatment process is essential for managing the waste safely and effectively. Proper function of a septic tank prevents the materials from overwhelming the system and protects the local environment by minimizing contamination of groundwater.

Filtering drinking water, storing rainwater, and managing stormwater runoff are functions related to other systems and not the primary purpose of a septic tank. A septic tank is specifically designed for on-site wastewater management, ensuring that contaminants are appropriately treated before being released into the surrounding environment.