What is meant by the term effluent?

Effluent refers specifically to treated wastewater that is discharged from a septic tank or similar wastewater treatment system. In a septic system, the treatment process involves separating solids from liquids, where the solids settle at the bottom of the tank and undergo anaerobic digestion over time. The liquid that remains, which has undergone treatment, is what is termed effluent. It is usually released into a drain field or other disposal area for further treatment in the soil before it re-enters the groundwater system.

Understanding effluent is crucial for septic inspectors since the management and quality of effluent directly affect both environmental health and public safety. The treatment process is designed to reduce harmful pathogens and pollutants present in the wastewater, making the effluent much safer for reintroduction into the environment compared to raw sewage.

The other options pertain to different aspects of the septic system or water management. Untreated sewage is waste that has not yet gone through any treatment process; solid waste refers to the solids that accumulate at the bottom of the tank; and surface water runoff describes the excess rainwater that flows over land, none of which accurately define effluent.