What is the primary purpose of a septic tank?

The primary purpose of a septic tank is to separate solid waste from liquid waste for treatment. In a typical septic system, when wastewater flows into the tank, it undergoes a process of sedimentation. Heavier solids settle at the bottom, forming a sludge layer, while lighter materials, such as fats and oils, float to the top creating a scum layer. This separation is crucial for the effective treatment of wastewater, as it prevents solids from clogging the drain field and allows the liquid effluent to be treated and dispersed safely into the soil.

By performing this vital separation, a septic tank not only facilitates the treatment of household wastewater but also helps in protecting groundwater quality. The process that occurs in the septic system ultimately leads to the breakdown of organic materials by bacteria, further contributing to the treatment process before the liquid is discharged into the drain field for final absorption and filtration into the soil.