What does the term 'effluent' refer to in the context of a septic system?

In the context of a septic system, 'effluent' refers specifically to the treated wastewater that exits the septic tank after undergoing a primary treatment process. When wastewater flows into the septic tank, it undergoes sedimentation and biological processes where solid materials settle to the bottom, forming sludge, while lighter materials like grease and scum float to the top. The liquid that remains in the middle layer is what is considered effluent. This effluent is then typically directed into a drain field or leach field, where it percolates through the soil for further treatment and eventual return to groundwater.

This definition is crucial for understanding the function and components of a septic system, as effluent is a key phase of the wastewater treatment process responsible for maintaining proper sanitation and environmental protection. Effective treatment of effluent is imperative to prevent contamination of the surrounding environment.