The wastewater from the house enters the system for breakdown. The tank contents settle and the heavy solids(sludge) sink to the bottom, the lighter waste forms a scum layer on top with the clarified water in the middle. The water then flows slowly to a second chamber, where it eventually makes its way into the leach field. Here the wastewater disperses through perforated pipes and a gravel layer to the soil. Percolating through the soil, organisms complete the breakdown process and this now clean water re-enters the groundwater system.