Glossary of Plumbing Terms


Acrylonitrile-Butadiene-Styrene. Rigid black plastic pipe used for drain and vent lines.

Back Flow Preventer

A device to prevent backflow into a potable water supply.

Back Pressure

Pressure that resists the flow of water into a piping system.

Back Siphonage

The negative pressure that causes backflow.


To remove excess air by opening a valve at the end of the pipe.

Catch Basin

Large underground container to collect dirt and debris from storm water runoff.

Check Valve

A type of backflow preventer installed in a pipe run that allows water to flow in only one direction.

Cleanout Plug

A plug in a trap or drain pipe that allows access for clearing an obstruction.

Corrosive Water

A water condition of low pH that causes corrosion in metal pipes, pool fixtures and pumps.


The barrier in the toilet tank that controls the water level in the toilet bowl.


A valve that directs fluid to various outlets. They are used in showers, tubs and sinks.

Dynamic Pressure

The pressure when the water is flowing.


Liquid waste in your septic system.


A mechanical device for pumping sewage from below the sewer line.


Panels of glass or other material used to form shower or tub stalls.

Fall / Flow

The proper slope or pitch of a pipe for adequate drainage.

First Draw

Water that has been sitting in pipes or plumbing fixtures overnight and comes out when taps are opened in the morning.


Any pipe part used to join together two sections of pipe.

Flexible Connector

A braided hose that connects a faucet or toilet to the water supply stop valve.


Gallons Per Hour. A measure of flow rates.


The process of applying a coating of zinc to a finished product to provide corrosion protection.

Gray Water

Waste water from sinks, showers, and bathtubs, but not toilets.

Grease Trap

A device used to capture grease entering a system before it reaches the sewer lines.


Heating, Ventilation, and Air Conditioning.

Hose Bibb

An outdoor faucet.

House Trap

U-shaped fitting with two adjacent cleanout plugs visible at floor level if main drain runs under floor.


A term referring to something submerged in water.

In-line Pump

Small pump which pumps fluid through a line on which it is supported and mounted.

Integral Stops

Stops that allows the shut off of water supply at the faucet for maintenance without shutting off the water supply to the entire house.


Closet bolts, used to mount toilet bowls to the closet flange.


One length of pipe.

Junction Box

Utility area where incoming current is connected in an electrical appliance.

Knockout Plug

PVC test plug.

Leach Field

Porous soil area, through which septic tank leach lines run, emptying the treated waste.


Loss of fluid usually due to mechanical breakdown or gasket wear.

Limit Stop

Faucet control unit used to adjust maximum water temperature.


A device installed in a drain line between a toilet and the soil stack to reduce solids to liquid form.

Metal fatigue

A breakage of a metal that can be caused by the bending and flexing or the expansion and contraction of a metal part past its endurance limit.

Municipal Water

Water supplied by a city or county for public use; tap water.


A short length of pipe installed between couplings or other fittings.


Not suitable for drinking.


Round rubber washer used to create a watertight seal.

Outlet / Discharge

The opening through which the water exits the pump.

Overflow Tube

The tube inside a toilet tank that directs water into the bowl in case the ball malfunctions.


Parts Per Million. A unit of measure for impurities in water.

Perforated Pipe

Pipe designed to discharge water through small, multiple, closely spaced orifices or nozzles, placed in a segment of its circumference for irrigation purposes.


Downward slope of a drain pipe in the direction of the water flow.


A fitting that connects pipes of different sizes together.

Return Circulation System

Tempered water from or near the point of usage which eliminates waste of hot water used for long runs.

Roller Hanger

A pipe hanger similar to a clevis hanger except that the yoke bolts to a roller rod instead of a metal strap.

Sanitary Fitting

Fitting that joins the assorted pipes in a drain, waste, and vent system, designed to allow solid material to pass through without clogging.

Scupper Drain

A drain normally located on a roof or deck that allows rain water to drain off.

Service Entrance

Pipe connecting the water company piping to the water meter.

Slide Bar

Type of shower component designed for the attachment of a hand-held shower.

Tank Fixture

A reservoir for flush water. On a conventional toilet, the ballcock, flush valve, and trip lever are installed in the tank.


T-shaped fitting with three openings that allow another pipe to be joined at a 90 degree angle, used to create branch lines.

Touchless Faucet

Commercially installed faucet or urinal valve that function using infrared sensor system.

Universal Plumbing Code

A system of procedures designed to provide consumers with safe and sanitary plumbing systems.

Vacuum Breaker

An anti-siphon device that prevents the backflow of contaminated water into the water supply system.


A pipe that allows air into a drain system to balance the air pressure, preventing water in the traps from being siphoned off.

Voral Tube

Flexible steel hose used for hand-held shower sprays.

Waste Shoe

Bathtub drain assembly.

Water Spot

Water surface in the toilet bowl once the flush is completed.

Well Casing

A steel or plastic pipe inserted into a drilled well to prevent dirt and debris from contaminating the water.


Usually a brass casting that holds both the hot and cold valves and the mixing chamber for the water.

Zero Soft

Water with a total hardness less than 1.0 grain per gallon.

Zone of Saturation

The layer in the ground in which all of the available voids are filled with water.

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