Plumbing Glossary of Terms

 Glossary of Terms:  Plumbing | The Moran Group



(Aristocraft bristone styrine)
Pipe used for waste, vent, and drain lines made of rigid plastic.

"A" Valve:

A valve used to manually shut gas off.

Access Panel:

For servicing purposes, an opening in a wall or ceiling near plumbing/electrical fixtures.


Increases the concentration of hydrogen ions when dissolved in water. Acid dissolves common metals.


The measurement of acid concentration in water.


For the purpose of waterproofing shower walls, it is a thermoplastic added to the surface of bathtubs and whirlpools.


A fitting that allows for different pipe types to unite.


A device that adds air into flowing water from the end of a faucet to reduce splashing.


A separation between the waste receptor and the fixture, appliance, or device that is indirectly connected.

Air Lock:

An air bubble in the line that blocks the flow of liquid on the suction side of the pump.


The measurement of a water supply's ability to neutralize acids.

Ambient Temperature:

The average temperature of the air surrounding an appliance.

Angular Discharge Tube:

A tube that changes the direction of water flow by 90 degrees.

Angle Stop:

Used for emergency repair, it is a shutoff mechanism between water pipes and a faucet.

Anode Rod:

For the purpose of extending the life of the tank, it is a rod installed in a water heater that reduces corrosion.


Prevents water from trickling back into the supply that is feeding into a sprinkler system.



Flow of water or other substances into the distributing pipes of a potable supply of water from unintended sources.

Back Flow Preventer:

Prevents water or other substances from traveling back into the main distribution system. A backflow preventer is required for sprinkler systems, handheld showers, pullout faucet sprouts, kitchen sprayers, and other various devices.

Back Pressure:

Pressure against the flow of fluid in a piping system.

Back Siphonage:

The reverse flow of liquid due to a partial vacuum in the pipe.


A clogged plumbing fixture due to drain stoppage.

Backwater Valve:

A valve within the sewer line that prevents sewage from reversing travel into the building.

Ball Check Valve:

A valve that utilizes a ball to seal an area and stop flow in a certain direction.


The fill valve that determines the flow of water from the water supply line to the toilet tank.

Basin Wrench:

A long-handled wrench with jaws mounted on a swivel that can reach nuts in a previously installed sink.

Basket Strainer:

A strainer that fits into a sink or shower drain; it allows water to run through, but catches food, hair, and other objects to prevent clogging.

Bidet (pronounced Bid-day):

Consisting of a washing basin, hot/cold faucet, and sprayer, it is mounted near a toilet for the purpose of washing one's self.


Bleeding is the process of draining a pipe, tube, or hose of excess air.


Blowbags are devices that clean drains. They are made up of a rubber bladder with a hose fitting on one end and a nozzle on the other. The blowbag is attached to a water hose and the hose is inserted into a clogged drainpipe. Water is expelled in pulses, forcing water through the clog.


A tank that heats water and turns it to steam for power or hot water.


Various parts of a drain system, less the main, riser, or stack.

Branch Vent:

A vent that connects 1+ single vents with a vent stack.

BTU (British Thermal Unit):

A unit of heat energy needed to raise 1 lbs. of water by 1 degree.


Catch Basin:

A below ground container with a grate that collects storm water run-off. It catches debris, preventing water pollution.


A type of bathroom faucet with a spout and handles that are 4 inches apart.


A cesspool is an underground excavation in the ground that receives the discharges of a drainage system. It retains the organic, solid matter and permits the liquids to seep through.

Check Valve:

A backflow preventer that only permits water to flow in one direction.

Circuit Vent:

A vertical vent drainage system run from the last two traps on a horizontal drain line to the main vent stack.


An underground rainwater storage container.

Cleanout Plug:

A cleanout plug provides access to a drain pipe to clear out obstructions.


Another phrase for toilet.

Closet Auger:

A rod that can access the built-in trap to remove clogs.

Closet Bend:

A fitting mounted below the toilet, connecting the closet flange with the toilet drain.

Closet Flange:

A closet flange is an anchoring ring that attaches to the closet bend, and then is secured to the floor.


A faucet or valve that regulates the flow of water; it is also known as a ballcock.

Common Vent:

A drain system within a building that connects 2+ fixture branches on the same level.

Compression Fitting:

A pipe connection where a nut and sleeve is placed over a tube, compressing it tightly around the tube as the nut is tightened; this forms a seal without soldering.

Compression Valve:

A valve used for water faucets. It opens and closes by raising and lowering a horizontal disk.


A hood for the vent pipe.

CPVC (Chlorinated Polyvinyl Chloride):

A plastic pipe used in some water supply systems, depending on code requirements.


Similar to a pipe, a construction of concrete that allows drainage underneath a road.


Desanco Fitting:

A compression adapter that attaches tubular brass fittings to PVC pipes.


To prevent debris build-up within the valve, a diaphragm is a flexible membrane within a valve that regulates water flow from the supply lines.

Dip Tube:

A tube with the purpose of bringing cold water to the bottom of the water heater tank.

Direct Tap:

A clamp on a branch line that takes it off of the main line.

Discharge Tube:

A discharge tube is an outlet tube that connects a disposer/sump pump to a drain line.

Disposal Field:

A series of trenches that distribute waste uniformly into the soil.

Dishwasher Tailpiece:

An adapter that unites a basket strainer to a drainpipe with a dishwasher inlet.


Used in showers, tubs, bidets, and sinks, they are valves that direct water to certain outlets.

Drip Leg:

A pipe with one closed end that is placed at a low point in the gas piping to collect and remove condensation.

Drum Trap:

This type of trap is no longer used. It was formerly used as a trap in sewer lines.

Duo Valve:

A hot and cold valve with a single on/off lever used for washing machines.


Abbreviation for Drain, Waste and Vent.


E Coli:

An abbreviation for Escherichia Coli, a bacteria that reveals fecal contamination.

Earthquake Strap:

A metal strap that secures a water heater to a building's frame or foundation.


Generally expressed as a percentage, a term that describes the ability to utilize energy.


Liquid waste from a Septic system.


A pipe fitting that changes the direction of the line.


A trim beneath a faucet handle that covers the faucet stem and the hole; the escutcheon is used for vanity purposes.

Expansion Tank:

A tank with thermal expansion that has the ability to absorb excess pressure.



For the purpose of adequate drainage, the accurate slope of a pipe.

Female Fitting:

A fitting in which another fitting or pipe is inserted.

Finish Plumbing:

Plumbing fixture installation to make a system usable.


The device within a plumbing system that provides a supply of water and or its disposal.

Flapper Valve:

A piece of equipment on the bottom of the toilet tank that opens and closes, regulating the flow of water from the tank into the bowl.

Float Ball:

A ball connected to the ballcock that rises and falls with the water within the tank. It regulates the ballcock as needed.

Floor Flange:

A piece of equipment that connects a toilet and floor drain.


A valve within a toilet that automatically shuts off after it reads a pre-set amount of water.

Flushometer Tank System:

A toilet flushing system that uses water pressure to flush instead of the traditional gravity flushing system.


Flux is a paste that assists with the fusion of copper pipes and fittings before soldering. The paste helps the fusion and prevents oxidation.


The amount of floor space taken by an appliance.

French Drain:

A covered ditch with a layer of stones or other material.


Gas Cock:

A plug valve that is installed and used between a main gas line and an appliance.

Gas Control:

A piece of equipment that controls gas pressure on a water heater.


A Gate manages the flow in a conduit, pipe, or tunnel.

Gate Diverter:

A lever on a tub that activates the diverter valve.

Gravity Operated Toilet:

A flushing system that uses the natural downward pressure of water in a tank to effectively flush the toilet.

Gray Water:

Gray water is waste from sinks, showers, and bathtubs.


Horizontal Branch:

Drain pipes that run laterally. They run from plumbing fixtures to waste stacks in a building or in the soil.

Horizontal Run:

The horizontal length between where the fluid enter a pipe and where it leaves.

Hose Bibb:

An outdoor faucet.

House Trap:

A u-shaped fitting that has two adjacent cleanout plugs.

Hubless (No-Hub):

A drainage pipe made of cast iron that utilizes neoprene gaskets and clamps.


A system that transports heat through circulated water.



The abbreviation for inside diameter.

Indirect Wastes:

A waste pipe that discharges gray water by discharging it into a plumbing fixture.

Instantaneous Water Heater:

A water heater that uses a heat exchanger coil to heat the water.



A toilet feature that directs water into the trapway to begin the siphon action.


A johnni-bolt or closet bolt is used to mount a toilet bowl to the closet flange.


Kafer Fitting:

A cast iron drainage pipe that attaches to the existing cast iron lines.

Knockout Plug:

PVC test plug.


Lavatory (Lav):

Another term for bathroom or restroom.

Leach Field:

For the purpose of emptying treated waste, a porous soil with septic tank lines running through it.


A leader is a pipe that carries rainwater to the ground or sewer.

Lock Nut:

A nut that joins two pipes together.



All branches connect to this main water supply.

Male Threads:

The threads that are seen on the outside of pipes and fittings.

Malleable Fittings:

A pliable fitting made of metal.


A type of fitting that connects branches to the main.


The moving part components of plumbing, heating, and cooling systems in a building.

Multi-Stage Pump:

A pump with multiple impellers.



A short length of pipe that is installed between fittings.

No-Hub Connector:

Used to connect different materials together. It consists of a rubber sleeve and a stainless steel band with hose clamps.



Abbreviation for Outside Diameter.


Used around valve stems, a rubber washer that creates a watertight seal.


Oakum woven hemp rope that has been treated with a waterproofing agent. It caulks bell and spigot pipe and fitting joints.

Outlet Sewer:

An outlet sewer is a pipe section that runs between a septic tank and drainage field in a septic system.



A material used on faucets that prevents leaks.

Packing Nut:

A nut that keeps the faucet in position and holds the packing material.

PB (Polybutylene):

A type of flexible, plastic tubing used in some water supply systems.

Peak Hour Demand:

The peak hour demand is the time of day when hot water demand is at its climax.


pH is the amount of hydrogen ion concentration in water. The pH scale measures the alkalinity and acidity.

Pipe Dope:

A nickname for a material that is applied to a threaded fitting to create a watertight seal.


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


The act of performing plumbing work.

Plumber's Putty:

Pliable putty that seals joints between drains and fixtures,

Plumbing Tree:

A set of drain waste, vent, and supply lines that have been pre-fabricated.


A rubber headed instrument that creates suction in a drain line or toilet and pushes a clog through the line.

Pop-Up Drain:

A type of drain assembly that uses lavatory lift rod or bath overflow plate lever. When it is lifted, the pop-up drain closes for the purpose of retaining water.


The opening in a burner head that allows gas or air-gas mixture to escape for ignition.

Positive Displacement Pump:

The PD pump makes a fluid motion by containing a fixed amount and moving it into the discharge pipe.

Pressure Balance Valve:

A shower mixing valve that maintains a balance between hot and cold water supplies by automatically regulating fluctuations in pressure. The result is constant temperature.

Pressure Tank:

A pressure tank is used in a well to pump water.

Pressure Tubing:

A pressure tube conducts fluids under pressure or at high temperatures.

PVC (Polyvinyl Chloride):

A PVC plastic pipe is used in non-pressure systems, such as drainage, waste, and vent systems.


Rated Storage Volume:

The amount of water within a tank.


A grinding tool that levels valve seats in faucets to improve the valve stem fit.

Recovery Capacity:

The amount of water in gallons/hour raised to 100 degrees at a given thermal efficiency,


A reducer connects different sized pipes together.

Return Circulation System:

A system that eliminates the waste of hot water for long runs; this system also adds storage.


A pipe that connects with a vent system, used to vent a fixture trap.

Reverse Trap Water Closet:

A water closet that has a siphonic trapway at the back of the bowl.

Rigid Pipe:

A pipe that transmits the backfill load to the foundation beneath the pipe.

Rim Holes:

A number of holes circulated around the toilet rim. The incoming water flows into the bowl through the holes, washing the inner surface of the bowl.


An assembly that connects a faucet and water supply stop valve. It is also a name of a supply line that goes from one story to the next.

Roof Flashing:

Installed to prevent leaks, it is a sheet metal at the break of a shingled roofline, sewer vents, and flue pipes.


Installation into the proposed location of the drain, waste, vent, and supply lines.

Rough-In Dimensions:

The measured length between the center of a waste/supply opening or fixture to a wall or floor.


A section of pipe that extends from supply to fixture or drain to stack.


Saddle Valve:

A valve mounted on a pipe run near a clamping device or fitting. It enters the side of the pipe and provides a water supply for a low-demand device.

Sanitary Fitting:

A fitting that is designed to allow solid material to pass without clogging a drain, waste, and/or vent system.

Sanitary Sewer:

A drain that takes wastewater away from the house to a disposal system such as a sewer system or septic tank.

Self-Rimming Sink:

A sink with a built-in lip of the same material that supports the vanity top.

Service Entrance:

A pipe that connects the water company supply to the water meter.


The distance from the top of the well to the top of the pump.


A drain outlet cover mounted below a wall-mount lavatory.

Siphon-Vortex Water Closet:

A type of toilet that has a trapway at the back of the bowl, integral flushing rim, and a water supply system that does not go into the trap.


A pipe that runs through a wall to allow another pipe through it.

Slip Joint:

A connection made with compression fittings.

Soil Stack:

A main drain line that all branch lines connect to carry waste to the sewer.


Melted metal alloy that fuses joints of metal together.


A spud is a threaded opening on a water heater tank.


A vertical main that reaches multiple stories; the main resides in the drain, waste, and vent system.

Stand Pipe:

A stand pipe is the name of several pipe types. A stand pipe is a vertical pipe that receives water from washing machines; a water supply for a fire sprinkler system, or a vertical pipe that has water pumped into it to produce a certain pressure.

Static Lift:

In a pump installation, the vertical length of space between the source and discharge water levels.

Stop Valve:

A valve beneath sinks and toilets that shuts off the water supply to one fixture without affecting the other.

Straight Cross:

A straight cross connects four pipes of the same diameter together.


A pit for draining, collecting, or storing water.


Sweating has two definitions. It is slang for soldering and a term for condensation that builds outside of pipes or toilet tanks.


T & P (temperature and pressure) Valve:

A T&P valve is a piece of safety equipment that expels extra pressure or heat from within the tank.


A piece of pipe that is fitted between a fixture outlet and its trap.

Tail Pipe:

The tail pipe is added below the jet assembly in a well system.


A tank is part of a toilet system. It is a reservoir for flush water. The tank houses the ballcock, flush valve, and trip lever as well.

Tank Cross:

A fitting installed between a well pump and a bladder tank with valve, gauge, and an outlet for a pressure-relief valve.

Tap Tee:

A tee made of cast iron; this tee has a threaded female inlet.


A t-shaped fitting that has three openings for branch lines.


A thermocouple is a small electric generator.

Thermostatic Valve:

For showers, this valve balances pressure and temperature control.


A curve in a drain line that traps sewer odors, preventing them from escaping into the atmosphere. All drains have "P" traps, but toilets, which have "S" traps.

Trap Arm:

In a drainage trap, the trap arm acts as a waste arm.

Trap Dip:

In a drainage trap, the trap dip is the u-bend.

Trap Primer:

A line that connects the cold water line to the drainage trap for the purpose of releasing small amounts of water into the trap to maintain the water seal.

Trap Seal:

A trap seal is the height of the water in a toilet bowl while not in use. It acts as a water seal to prevent sewer gases from seeping into the home.


A connection between the bowl and waste outlet in a toilet. Trapways are measured by the largest diameter ball that can pass through it.

Trip Lever:

The handle and actuating arm on a toilet tank or the lever that controls the drain on a bathtub.



A one-piece stop and riser.


A three piece fitting that joins two pipes together with the ability to disconnect without cutting the pipe.

Usable Storage:

The percentage of hot water that can be taken from a tank without lowering the temperature to the point it is not considered hot.


Vacuum Breaker:

A device that prevents the backflow of impure water into the water supply system.

Valve Seat:

A part of the valve that is stationary. Water flow halts when the moveable portion of the valve meets the valve seat.


For the purpose of preventing siphoning, a pipe that brings air into the drain system to balance air pressure.

Vent Header:

Several vents connect to the vent header, which leads to the vent stack.

Vent Stack:

The top portion of a soil stack, that allows gases and odors to escape.

Vent System:

A vent system provides an airflow to and from the drainage system. The air protects against siphoning and back-pressure.


For the purpose of creating a suction in a vacuum pump, a venturi is a short, narrow tube that increases the speed of the flow of a fluid and decreases the fluid pressure.


Viscosity is the resistance of fluid flow due to molecular friction.

Vitreous China:

A non-porous ceramic used for bathroom fixtures.


Washdown Water Closet:

A water closet with a front siphon trapway and integral flushing rim.

Waste Arm:

A waste arm is an extension pipe that extends from a fixture into the wall.

Waste & Overflow:

A waste and overflow is a drain assembly for a bathtub. It has an outlet at the top that removes any overflow of water and a drain at the bottom that removes wastewater.

Wet Vent:

A vent that also acts as a drain.


A type of bathroom faucet with separate spout and handles.


For the purpose of making branch lines, a Y-shaped fitting with three openings.



A casting with hot and cold valves and the mixing chamber for water.

Yoke Vent:

A yoke vent prevents pressure changes in the stacks by connecting upward from a soil or waste stack to the vent stack.


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