What is the primary purpose of a septic tank?

The primary purpose of a septic tank is to treat and store wastewater. In a septic system, wastewater from bathrooms, kitchens, and laundry flows into the septic tank, where it undergoes a natural treatment process. The tank serves as a settling chamber, allowing solids to settle to the bottom, forming sludge, while lighter materials like grease float to the top, forming scum. This process helps to separate the solids from the liquids, which then allows the treated wastewater to be discharged into the drainage field or leach field, where further treatment occurs through soil filtration.

This option emphasizes both the treatment aspect and the temporary storage of wastewater until it can be further processed, differentiating it clearly from simply accumulating waste indefinitely or solely filtering solids. Other provided options, while referencing related aspects of septic systems, do not adequately capture the dual role of wastewater treatment and storage that a septic tank performs.