What is the main function of a septic tank?

The primary function of a septic tank is to store and treat domestic wastewater generated from households. In a septic system, wastewater flows into the septic tank, where it undergoes primary treatment. This involves the settling of solids to the bottom, forming sludge, while lighter materials, such as grease and oils, float to the top as scum. The tank provides a controlled environment for anaerobic bacteria to break down the organic matter in the wastewater, which ultimately reduces pollutants before they are further treated in the leach field or soil.

The septic tank is designed to handle sewage on-site, ensuring that it does not contaminate ground or surface water sources. It is not responsible for filtering air, managing stormwater runoff, or supplying fresh water, which clarifies why the other options do not accurately represent the main function of a septic tank.