Sewer & Septic Glossary

Septic System Anatomy

• Septic Tank — A septic tank is a watertight underground container — typically made of concrete, fiberglass, or polyethylene — that receives all wastewater from a home or building not connected to a municipal sewer system.
• Drain Field (Leach Field) — The drain field — also called a leach field or soil absorption system — is the final treatment stage in a conventional septic system.
• Distribution Box (D-Box) — A distribution box — commonly called a D-box — is a small concrete or plastic box installed between the septic tank and the drainfield.
• Baffle — A baffle is an internal component installed at both the inlet and outlet openings inside a septic tank.
• Scum Layer — The scum layer is the top layer inside a septic tank, consisting of materials that are lighter than water and float: fats, greases, oils, soap residue, and other buoyant particles from household wastewater.
• Sludge Layer — The sludge layer is the bottom layer inside a septic tank — the heavy, dense accumulation of solid waste that settles by gravity.
• Effluent — Effluent is the partially treated liquid wastewater that exits the septic tank and flows toward the drainfield for final treatment.
• Effluent Filter — An effluent filter is a cartridge-type filtering device installed in the outlet baffle of a septic tank that provides an additional barrier against solids reaching the drainfield.
• Septic Pump — A septic pump (also called an effluent pump or dosing pump) is a submersible electric pump installed in a pump chamber or the septic tank itself to move effluent to the drainfield when gravity flow is not possible.
• Lift Station — A lift station (also called a pump station) is a wastewater pumping facility that collects sewage or effluent that cannot flow by gravity and pumps it uphill to a higher elevation in the system.
• Riser — A septic riser is a vertical extension pipe installed above a septic tank lid to bring the access point up to or near the ground surface.
• Inlet/Outlet Tee — An inlet tee and an outlet tee are T-shaped pipe fittings installed at the points where wastewater enters and exits the septic tank.

Septic Processes & Problems

• Septic Tank Pumping — Septic tank pumping is the process of removing accumulated sludge and scum from a septic tank using a vacuum truck.
• Septic Inspection — A septic inspection is a professional assessment of a septic system's condition and compliance.
• Septic Failure — Septic failure occurs when a septic system can no longer adequately treat wastewater — either because components have failed mechanically or because the system's treatment capacity has been exceeded.
• Drain Field Saturation — Drain field saturation occurs when the soil in the drainfield becomes unable to absorb and treat effluent at the rate it is being delivered.
• Biomat — Biomat (biological mat) is a dense, gelatinous layer of anaerobic bacteria and their byproducts that forms at the soil interface in a drainfield trench — the boundary between the gravel bed and the native soil below.
• Hydraulic Failure — Hydraulic failure occurs when more water enters a septic system than it can process and absorb.
• Septic Backup — A septic backup occurs when wastewater cannot flow forward through the system and reverses direction, appearing in the lowest plumbing fixtures in the home — typically basement floor drains, basement tubs, or ground-floor toilets.
• Anaerobic Bacteria — Anaerobic bacteria are microorganisms that live and function without oxygen.
• Septic System Rejuvenation — Septic system rejuvenation is a non-excavation rehabilitation process designed to restore drainage capacity to a failing or partially failed drainfield without the cost and disruption of full system replacement.

Drain & Sewer

• Hydro Jetting — Hydro jetting is a drain and sewer cleaning method that uses high-pressure water — typically 1,500–4,000 PSI — delivered through a specialized nozzle to scour the interior walls of pipes clean.
• Drain Snaking — Drain snaking — also called mechanical augering or cable cleaning — is a drain clearing method that uses a rotating steel cable (the snake or auger) to punch through or retrieve blockages from drain and sewer lines.
• Sewer Line — A sewer line (also called a sanitary sewer line or sewer main) is the underground pipe that carries wastewater from a building to either a municipal treatment system or a private septic system.
• Lateral Line — A lateral line is the section of sewer pipe that runs from a private property to the municipal sewer main in the street.
• Cleanout — A cleanout is a capped pipe fitting installed in a sewer or drain line that provides direct access for cleaning, inspection, and clearing blockages without disassembling plumbing fixtures.
• P-Trap — A P-trap is the curved pipe fitting found beneath every sink, tub, and shower drain — the U-shaped section visible under most bathroom and kitchen sinks.
• Vent Stack — A vent stack is the vertical pipe in a plumbing system that extends from the drain lines up through the roof of the building to the outside air.
• Tree Root Intrusion — Tree root intrusion occurs when the roots of trees and large shrubs grow into sewer or drain lines through cracks, loose joints, or deteriorated pipe sections.
• Pipe Belly (Sag) — A pipe belly (also called a pipe sag) is a low spot or downward depression in an underground sewer or drain line caused by soil settlement, inadequate support during installation, frost heave, or soil erosion beneath the pipe.
• Blockage vs. Clog — In plumbing, a clog typically refers to a partial or complete obstruction within a single fixture's trap or short drain line — a sink clogged with hair and soap, a toilet clogged with too much paper, or a kitchen drain clogged with food debris.
• Camera Inspection — A drain or sewer camera inspection uses a waterproof camera mounted on a flexible cable to visually examine the interior of drain and sewer pipes.

Commercial & Specialized

• Grease Trap — A grease trap is a plumbing device installed in the drain system of a commercial kitchen that captures fats, oils, and grease (FOG) from wastewater before it enters the sanitary sewer.
• Grease Interceptor — A grease interceptor (sometimes called a large-capacity grease interceptor or LCGI) is a large underground tank — typically 500–2,000+ gallons — installed outside or beneath a commercial facility to handle the total grease-laden wastewater flow from a commercial kitchen.
• Sand Trap (Carwash) — A car wash sand trap — also called a grit chamber, sand interceptor, or automotive waste separator — is an underground tank or chamber installed in the drain system of a car wash facility to capture sand, grit, silt, and heavy debris before wastewater enters the sanitary sewer.
• Oil/Water Separator — An oil/water separator (OWS) is a treatment device that separates petroleum-based hydrocarbons (motor oil, diesel, gasoline residues, hydraulic fluid) from wastewater before discharge to the sewer system or the environment.
• Lift Pump — A lift pump (or sump lift pump) is a submersible pump used to move wastewater from a low-elevation collection point upward to a higher elevation in the drain or sewer system.

Regulatory & Homeowner

• Percolation Test (Perc Test) — A percolation test (perc test) is a soil evaluation that measures how quickly water absorbs into the ground at a specific location.
• Septic System Permit — A septic system permit is the regulatory authorization required from a local government (typically a county environmental services department) before installing, significantly modifying, or replacing a private septic system in Minnesota.
• Minnesota Pollution Control Agency (MPCA) — The Minnesota Pollution Control Agency (MPCA) is the state agency responsible for protecting Minnesota's air, land, and water quality, including oversight of private sewage treatment systems.
• SSTS (Subsurface Sewage Treatment System) — SSTS stands for Subsurface Sewage Treatment System — the formal regulatory term used in Minnesota for private on-site wastewater treatment systems (commonly called septic systems).
• Maintenance Contract — A maintenance contract (also called a service agreement or pumping contract) is a scheduled service arrangement between a property owner and a septic or drain service company that ensures regular maintenance is performed on a set timetable without the owner needing to track and schedule each visit independently.

Have a question not covered here?

Call us at 612-816-8013 or visit our FAQ page for answers to common homeowner questions about septic and sewer service in Minnesota.