How does a septic tank function?

A septic tank functions primarily by separating solids from liquids. This separation is a critical process that occurs within the tank. When wastewater enters the septic tank, it is composed of both solids and liquids. The tank allows for the natural settling of heavier solids at the bottom, where they form a sludge layer. Lighter materials, such as fats and oils, float to the top, creating a scum layer. The liquids in the middle, which are mostly clarified wastewater, flow out of the tank into the drain field for further treatment and absorption into the soil.

This biological and physical process is vital for the effective treatment of wastewater in systems not connected to municipal sewer lines. By separating the solids and liquids, the septic tank helps prevent clogs and ensures that only relatively clear effluent is discharged for further treatment in the leach field.