What is the main function of a septic tank?

The main function of a septic tank is to provide for the separation of solids and liquids. In a septic system, wastewater from household toilets and drains enters the tank, where gravity allows the heavy solids to settle at the bottom, forming a sludge layer. Lighter materials, such as oils and grease, float to the surface, creating a scum layer. This separation of solids and liquids is crucial as it allows the liquid effluent, which is relatively clear, to flow out of the tank into the drain field while preventing the solids from leaving the system. This process helps manage and treat wastewater in an efficient manner, serving as the first step in the overall treatment within a septic system.

The other options do not accurately describe the main function of a septic tank. For example, while the tank does collect fats, oils, and grease, that is not its primary role. Additionally, septic tanks do not typically treat wastewater to the level required for treatment level 3, as their primary function is separation rather than advanced treatment. Lastly, stating that none of the answers apply would contradict the established role of the septic tank in wastewater management.