Absorption Field: A leaching area within the soil that receives the liquid effluent from the laterals and distributes it to an area where it can seep into the soil.

Active System: A septic system that requires external energy and mechanical parts to operate.

Aeration Chamber: A volumetric container that is normally made of concrete, fiberglass, or plastic. It is designed to hold equipment that brings oxygen-rich air into the effluent.

Aerobic Bacteria: These are odorless, efficient strains of sewage-digesting bacteria that live in oxygen-rich environments.

Anaerobic Bacteria: Slightly less efficient strains of digesting bacteria that live in oxygen devoid environments.

Biomat: A black, slime by-product of anaerobic bacteria that forms around the distribution component and surrounding soil. Biomat can cause septic system problems if not treated.

Black Water: Influent that contains waste products.

Cesspit: A loosely lined pit that is dug in the ground to allow liquid effluent to seep out of the cesspool into the ground while capturing the solids in the pit.

Clear Zone: The middle layer of brownish, murky liquid in the septic tank that is composed of water and small suspended microscopic matter.

Distribution Box: A hollow cylindrical or cubical structure that is normally composed of fiberglass, plastic, steel, or concrete. It is located in the ground underneath the septic tank outlet and the distribution field.

Distribution Cell: A constricted trench that holds a perforated piping system that is covered in washed gravel to allow effluent to flow into it from a distribution component and be dispersed evenly into the ground.

Distribution Component: A seepage pit, drainfield, or mound that is used to distribute effluent into the ground.

Distribution Field: Also known as an absorption field.

Distribution Laterals: A distribution component that extends from the main distribution pipe to the ends of the distribution field. It is designed to evenly distribute effluent into the ground.

Drainfield: Also known as absorption field.

Dry Well: A hollow, porous chamber in the ground that is lined with bricks or blocks to allow effluent to flow in from a septic tank and be evenly dispersed into the ground.