Which of the following functions does a septic tank NOT perform?

The correct answer is related to the specific functions of a septic tank within the wastewater treatment process. A septic tank is primarily designed to settle solids, provide anaerobic digestion, and store wastewater.

The settling of solids occurs as wastewater enters the tank, where heavier particles settle to the bottom, forming sludge. This allows the liquid effluent above to flow into the distribution system. Additionally, the conditions within the tank promote anaerobic digestion, a process wherein bacteria break down organic matter in the absence of oxygen, helping to reduce solids and pathogens.

Storing wastewater is a fundamental function of a septic tank, as it holds the sewage until it can be processed further in the drainage field.

However, filtering water is not a primary function of a septic tank itself. While the effluent is indirectly filtered as it moves through the soil in the leach field, the septic tank does not actively filter water like a conventional filter would. Instead, its main role is in the initial treatment and storage, with filtration being part of the subsequent process that occurs in the soil after the liquid effluent is discharged from the tank.