Leachfield: A subsurface leaching area within the soil that receives the liquid effluent from the distribution laterals and distributes it over a specified area where it is allowed to seep into the soil.
Aerobic Bacteria: Odorless, highly efficient strains of sewage digesting bacteria that live only in the presence of oxygen.
Anaerobic Bacteria: Less efficient strains of sewage digesting bacteria that live only in the absence of oxygen.
Biomat: Black, slimy growth and by-product of anaerobic bacteria that grows at the interface of the distribution component and the surrounding soil. If neglected, the biomat becomes impermeable and can cause septic system backups and failure.
Clear Zone: The middle layer of gray or brownish, murky liquid in a septic tank that is mostly comprised of water with small microscopic matter in suspension.
Distribution Box: A hollow cylindrical or cubical structure constructed of concrete, fiberglass, plastic or steel, located underground between the septic tank outlet and the distribution field.
Distribution Cell: A narrow trench that contains a perforated piping system embedded and covered in washed gravel in such a manner that effluent can flow into it from a distribution component and be uniformly dispersed into the ground.
Drainfield: Another name for leach field.
Effluent: Wastewater which flows out of a septic tank and into the leachfield.
Leach field: Another name for a distribution or drain field.
Passive System: A septic system that does not require external energy and mechanical components to function.
Septic Tank: A tank made of concrete, fiberglass, plastic or steel used in a septic system that accepts influent and is designed to separate and hold the solid matter of continuously flowing sewage. The tank also holds bacteria required for the digestion of the solids.
Sludge Layer: The bottom layer of matter in a septic tank that is heavier than water and comprised mostly of solids.
System Failure: A condition when a distribution field becomes saturated and foul-smelling effluent appears on the ground above the distribution component creating a health and environmental hazard.
Vent Pipe: A vertical pipe made of plastic, steel, clay, or cast iron, that is connected to a component of a septic system that allows displaced air to flow to the atmosphere.
Vented Cover: A cover made of concrete, fiberglass, steel or plastic that has an integral vent pipe or opening.