Which of the following illustrates the function of a septic tank?

The function of a septic tank is primarily to separate solids from liquids in wastewater. This process is crucial for the treatment of onsite wastewater systems. When wastewater from a home flows into the septic tank, the tank allows solids to settle at the bottom, forming sludge, while lighter materials like fats and oils float to the top, creating a scum layer. The clarified liquid in between is known as effluent, which is then directed to a drain field for further treatment and dispersal into the soil.

This separation process is vital because it prevents solids from clogging the subsequent components of the wastewater treatment system and ensures that only the liquid effluent proceeds to the next step in the treatment process. Understanding this role is fundamental for anyone involved in the management and maintenance of onsite wastewater systems. The other choices do not reflect the primary function of a septic tank.