How it works

All water runs out of your house from one main drainage pipe into a septic tank. The septic tank is a buried, water-tight container usually made of concrete, fiberglass, or polyethylene. The liquid wastewater (effluent) then exits the tank into the drain field. The drain field is a shallow, covered, excavation made in unsaturated soil. Pretreated wastewater is discharged through piping onto porous surfaces that allow wastewater to filter though the soil. Finally, the wastewater percolates into the soil, naturally removing harmful coliform bacteria, viruses and nutrients. The recycled water then returns to underground aquafers. 

When wastewater enters your septic tank, it naturally divides into three parts:  Solids sink to the bottom and form a sludge layer. Liquids stay in the middle and form a layer of mostly water. Oils and fat rise to the top in a scum layer.  The liquid layer accounts for 90 percent of your tank’s capacity, meaning excess water use can affect the tank’s function over time. Ideally, water in your tank flows through over several days while materials on the bottom are broken down by bacteria.  The liquid flows into the effluent chamber where it is stored until it is pumped out into the field.