New sewage should enter the septic tank no less than 15 inches below the

New sewage should enter the septic tank no less than 15 inches below the

• A. Scum layer
• B. Inlet pipe
• C. Bottom of tank
• D. Outlet tee

Answer: (A)

Entering the septic tank well below the surface scum layer helps keep the floating scum from being disturbed by the incoming waste. The scum layer is fats, oils, and grease that rise to the top, and if the inflow hits near or within that layer, it can churn up the scum and push solids toward the outlet, reducing effluent quality and potentially clogging the drain field. By placing the inlet at least 15 inches below the scum, the flow mixes with liquid below the surface, allowing most solids to settle at the bottom and maintaining a stable separation between scum and clarified effluent. The other elements (bottom of the tank, the inlet location relative to the pipe, or the outlet tee) don’t address preventing scum disturbance in the same effective way as ensuring the inlet is far enough beneath the scum layer.

Entering the septic tank well below the surface scum layer helps keep the floating scum from being disturbed by the incoming waste. The scum layer is fats, oils, and grease that rise to the top, and if the inflow hits near or within that layer, it can churn up the scum and push solids toward the outlet, reducing effluent quality and potentially clogging the drain field. By placing the inlet at least 15 inches below the scum, the flow mixes with liquid below the surface, allowing most solids to settle at the bottom and maintaining a stable separation between scum and clarified effluent. The other elements (bottom of the tank, the inlet location relative to the pipe, or the outlet tee) don’t address preventing scum disturbance in the same effective way as ensuring the inlet is far enough beneath the scum layer.