What constitutes a septic tank?

A septic tank is defined as a watertight container that processes sewage from a household or facility. This tank plays a crucial role in on-site wastewater management systems. The primary function of a septic tank is to receive wastewater and allow solids to settle at the bottom to form a sludge layer, while lighter materials like grease and oils float to the surface to form a scum layer.

The design of a septic tank enables anaerobic bacteria to break down the organic matter in the sewage, which is essential for the treatment process. It’s important to ensure that the tank is watertight to prevent contamination of groundwater and to effectively hold and treat sewage before it enters the drain field for further filtration and absorption into the soil.

Other options describe systems that do not align with the function of a septic tank. For instance, rainwater storage systems are unrelated to sewage processing, while filtration systems for stormwater are designed for different purposes entirely. Lastly, portable toilets serve a different function, primarily providing temporary sanitation facilities rather than engaging in the treatment of residential sewage.