A system typically has 3 parts:

1. Plumbing from the house: pipes that carry wastewater to the septic tank.
2. A septic tank: a water-tight container for collection and initial treatment of wastewater.
3. An effluent treatment system: an underground system for distribution into the soil, final treatment, and reintroduction of wastewater into the environment (effluent comes from the septic tank).
   • The effluent treatment system is usually a drainfield; also known as laterals, trench, absorption field or leach field.