How does a septic system work?

A septic system in an onsite water treatment system, where the waste is collected, treated and redistributed back into the earth.

The typical onsite wastewater treatment system is comprised of two main components: A holding tank and a soil absorption system.

The holding tank, known as a septic tank, is made of fiberglass, concrete or polyethylene. The wastewater is collected in the septic tank, where it will be held for initial treatment. The tanks are separated into two chambers. The tank is designed to hold the waste long enough for the solids to sink to the bottom and the grease to float to the top. Once this occurs, the clear liquid in the center, the effluent, flows to the soil absorption system for secondary treatment.

The soil absorption system is known as a drainfield or leach field. Each individual drainfield is designed to efficiently distribute the partially treated wastewater, the effluent, into the soil for secondary treatment. The soil treats the effluent and then distribute it into the ground water.