A typical septic system has four main components: a pipe from the home, a septic tank, a drainfield/leachfield, and the soil. Microbes in the soil digest or remove most contaminants from wastewater before it eventually reaches groundwater.
Pipe from the house:
All of your house hold wastewater exits your home through a pipe to the septic tank.
Septic Tank:
The septic tank is buried, watertigh container typically made of concrete, fiberglass, or polyethylene. It holds the wastewater long enough to allow solids to settle out, forming sludge, and oil and grease to float to the surface as scum. It also allows partial decompositions of the solid materials. Compartments and a T-shaped outlet in the septic tank prevent the sludge and scum from leaving the tank and traveling into the leach field/drain field area.
Leach fields/Drain fields:
The wastewater exits the septic tank and is discharged into the leach field/drain field for further treatment by the soil. The partially treated wastewater is pushed along into the leach field/drain field for further treatment everytime new wastewater enters the tank. If the leach field/drain field is overloaded with too much liquid it will flood, causing sewage to flow to the ground surface or create backups in plumbing fixtures and prevent treatment of all wastewater.
Soil:
Septic tank wastewater flows to the leachfield/drainfield, where it percolates into the soil, which provides final teatment by removing harmful bacteria, viruses, and nutrients. Suitable soil is necessary for successful wastewater treatment.