Septic System Owners' Glossary

When you speak with your septic system service professional, it's nice to know what you're talking about.

Here are some commonly used terms relating to septic systems and septic system drain fields.


Biological mat is made up of organic matter, minerals, microorganisms and sulfites, which are the byproduct of decomposition. The biomat is a critical part of a septic system as it processes out pathogens before the effluent is returned to the local water table.

Aerobic Bacteria

Aerobic means with oxygen. Aerobic bacteria live in the soil surrounding the drainfield trenches. They are responsible for removing pathogens and other undesirable constituents in septic system effluent before it is returned to the local water table.

Anaerobic Bacteria

Bacteria that is capable of existing without oxygen or with an extremely small amount. This type of bacteria exists within the drainfield trenches and are responsible for keeping the biomat in check\



Calcium Polysulfide

A chemical traditionally used in older style lime sulfur formulas designed to reflocculate, or return absorption ability to clay laden soil, it’s characteristics include a high pH and the strong odor of sulfur.


a cistern, well, or pit for retaining the sediment of a drain or for receiving the sewage from a house.

Clay Soil

Found in all parts of the country, clay acts as a good filter because the particles are so fine. For that reason it is a poor choice for septic system drainfields because it is subject to forming a hardpan surface when exposed to sodium carried in household wastewater.

Distribution Box (D-box)

The D-box performs just as it’s name suggests. It distributes liquid effluent from the septic tank to the various “legs” of the drainfield.

Drain Field (drainfield)

Also known as leach field, or absorption bed its function is to collect and process liquid effluent from the septic tank before it is returned to the water table. There are several different designs of drain fields in current use. They all have in common the fact that the ability of the native soil to absorb water is critical to their proper functioning.

Drain Field Problem

There are many factors that can contribute to septic drain field failure. Among the most common are grease and organic overload, hydraulic overload and last but not always recognized sodium bonding.


Eco-friendly products prevent or reduce contributions to air, water and land pollution.


Polluted water, such as the outflow from a sewage treatment facility or septic system.

Gravity Fed Septic System

The most common septic system design depends on gravity to move effluent from the household to the septic tank then to the leach field.

Hydro Jet

Brand name for power rodding, which consists of cleaning out drainage pipes with water at high pressure coming from a nozzle that sprays in a 360 degree pattern. It is used to knock solids from the insides of the pipes, which are then pumped to remove the dislodged debris.

Infiltrator Septic System

A system of chambers buried in a gravel trench to form a drainfield. The chambers perform a similar function as drainpipes in the leach bed.

Leach Field

AKA Leach bed, drain field, drainfield, absorption bed. Its main function is to process wastewater from on-site septic systems.

Mound System

A configuration of drainfield in which a mound of select drainage soil is piled on top of the natural soil in order to allow enough processing area before the treated effluent is returned to the local water table.  This type of system is called for when the local water table is not very far from the surface.


Perc for short, as in Septic Perc, it’s the ability of soil to allow water to pass through it. A “perc” test is often required before a site can be selected for septic system installation, or before finalizing a real estate transfer.


(potential hydrogen) is a scale of acidity from 0 to 14. It tells how acidic or alkaline a substance is, acidic solutions, 0 - 6 on the scale, are considered low pH, alkaline solutions have higher pH, 8 – 14 on the scale. Stream water has a neutral pH and reads about 7 on the scale.

Pump Station

Sewer pumping stations (also called lift stations) are used to move wastewater to higher elevations in order allow transport by gravity flow.


A septic-tank riser extends from the surface of the ground to the septic tank lid.  The purpose of this device is to eliminate the need to dig to gain access to your septic tank's lid for inspection or repairs.

Root Intrusion – When trees and shrubs are planted on or near the drainfield there is a good possibility that roots are clogging septic drain lines. 

Scum Layer

Refers to the layer of soap and grease that floats on the surface of the contents of the septic tank.

Seepage Pit

A seepage pit, sometimes called a leaching pit, leaching pool, or incorrectly a cesspool, is a covered pit with an open-jointed or perforated lining through which septic tank effluent seeps into the surrounding soil.

Septic Odor

There are several conditions that can cause a lingering septic odor near and around a septic tank or drainfield. Improper venting, weather conditions and a full septic tank are all possible causes. The septic smell is caused by sulfur and methane given off by decomposing organic matter.

Septic Problem

There are many problems that can occur in a septic system among the most common are septic system drain field failure, which can be caused by grease overload, water overload, hardpan soil and broken pipes.

Septic Tank

A holding place for household sewage where the decomposition process begins.  The partially processed effluent is then moved to a drainfield, leach field or seepage pit for further treatment before returning the treated water to the water table.

Shock Treatment

A septic system chemical soil treatment meant to shock the soil due to the large quantity applied in one application.


Salt. Sodium can cause hardpan conditions in septic system drainfields where clay is a constituent of the soil. Wastewater picks up sodium from cleaning products and salt in our diet. Households using sodium charged water softeners and putting the softeners backwash water into the drainfield are at increased risk of drainfield failure.

Terra Lift

A process of fracturing the soil then injecting Styrofoam-like beads into the soil to improve the soil’s ability to absorb water.


Any water that has been used for cleaning, bathing, toilet, etc. is considered wastewater or effluent.

Water Table

or Groundwater Table is the natural level at which the soil is saturated with water. The water table fluctuates both with the seasons and from year to year because it is affected by climate and by the amount of precipitation. It also is affected by withdrawing excessive amounts of water from wells or by recharging them artificially.