Glossary of Plumbing Terms

Plumbing Glossary of Terms

When it comes to plumbing, there’s a lot to know, from fittings to systems to repair techniques. There are many industry-specific plumbing terms that can be difficult for even the most intelligent homeowners to understand. A-1 American has put together a list of plumber terms in hopes that they make sense and help you make important decisions. As plumbing experts, we have compiled an A to Z glossary of plumbing terms to provide easy access to terminology that affects you and your home. If there’s a plumbing term you don’t find here, or if you have plumbing questions in general, contact us online, call us at 757-425-2400 or send us a message on our A-1 American Facebook page, and we will be happy to explain or answer your inquiry.

Glossary of Terms for Plumbing

1/8 bend offset: The 1/8 bend offset is a fitting used to set a pipe around an object.

Access Panel: Wall, ceiling or floor panels that allow access to plumbing or electrical service.

Adapter: This fitting joins pipes made of different sizes and materials.

Air Chambers: Pressure-absorbing devices that are installed at the end of long runs of pipe close to valves and faucets to eliminate water hammer.

Air Gap (Drainage System): The unobstructed vertical distance from the outlet of a water pipe to the flood level rim of the receptacle where it’s discharging.

Air Gap (Water Distribution System): The unobstructed vertical distance between the lowest opening from any pipe or faucet supplying water to a tank, plumbing fixture or other device to the flood level rim of the receptacle.

Air Lock: A bubble of air that restricts the flow of water in a pipe.

Auger: A flexible metal rod with a cutting or clearing device on one end. It’s used to clear clogs in drains.

Backflow: The flow of water, liquids or substances into distributing pipes of a potable water supply from any source or sources other than the intended source. Back siphonage is a type of backflow.

Back Siphonage: The flowing back of used, contaminated or polluted water from a plumbing fixture or vessel into a potable water supply caused by negative pressure in the pipe.

Ball Joint: A part of a joint shaped like a sphere that rests in a socket.

Branch Line: A supply pipe that carries water to a fixture.

Branch Vent: A pipe that connects the drain of a single fixture to the vent stack.

Building Drain: A part of the lowest piping of a drainage system that receives discharge from soil, waste or other drainage pipes inside the walls of a building or house, and conveys it to the building sewer beginning 3 feet beyond the building wall.

Bushing: A fitting that is threaded inside and out, and joins pipes made of different sizes.

Cap: A fitting that covers or seals the end of a pipe.

Circuit Vent: Vents that are positioned from the final traps of a horizontal drain line leading up to the primary stack of vents. They are usually found in drainage systems.

Cleanout: An opening that provides access to a drain or sewage pipe for clearing blockages. It’s closed by a removable plug.

Closet Flange: An anchoring ring that attaches to the closet bend. It’s secured to the floor.

Compression Fitting: A connector used on copper and plastic pipes that forms a watertight seal when the body and nut are tightened by squeezing the ring around the pipe. It’s composed of a threaded body, a compression nut and a compression ring.

Copper Piping: Water line made of copper or a copper alloy that is primarily used for potable, or drinkable, water. Copper pipe is usually rigid and the tubing is flexible. Copper will not rust and has a long life cycle, but it can corrode, which could cause leakage.

Coupling: A fitting that connects two straight runs of pipe.

CPVC: CPVC stands for chlorinated poly-vinyl chloride. This pipe can be used for both hot and cold potable water piping.

Cross Connection: A physical connection or arrangement between two otherwise separate piping systems, one of which contains potable water and the other contains either water of questionable safety or steam, gas, or chemical, whereby there may be a flow from one system to the other. The direction of flow depends on the pressure differential between the two systems. (See Backflow and Back siphonage for more details.)

Discharge Drain: A drain that discharges water into the ground through a channel or into a drain system. French drains are an example of a discharge drain.

Disposal Field: An area containing a series of trenches lined with coarse aggregate and conveying the effluent from the septic tank through vitrified clay or perforated non-metallic pipe. It’s laid in such a manner that the flow will be distributed with reasonable uniformity into natural soil.

Drain: Any pipe that carries wastewater in a building or house’s drainage system.

Drain Trap: A U-shaped passage in a drain line or at a fixture which stays filled with water to keep sewer gases from escaping from the drain into living spaces.

Dry Fit: A trial connection of pipes without using adhesives for the purpose of checking measurements.

Ell: An elbow joint with hubs on both ends that is used in making an angled connection between two straight runs of pipe.

Energy Star: An international standard for energy efficiency originating in the United States. Electrical, gas and other appliances must conform to certain energy standards to qualify for an Energy Star rating. Dishwashers, refrigerators, washing machines and water heaters are examples of appliances that can be Energy Star rated.

Faucet: A fixture that controls water flow. Most sink faucets have a mixing valve that allows the user to change the temperature of the water by changing the ratio of hot to cold. Faucets can come with either two handles, one for hot and one for cold, or with a single lever handle that changes the mix ratio.

Faucet Screen: A tiny metal screen found in the faucet arm nozzle used to catch small debris in the water system.

Flange: The end of a pipe with an extended rim to give a finished appearance.

Flapper: A hinged, movable part of a shut-off valve that prevents or shuts off flow. A common type of flapper is found at the bottom of a toilet water tank, and it works by raising up to start the flush cycle. It closes when the tank is empty, allowing it to refill.

Float Valve: A control valve that shuts off water at a predetermined level or capacity. A float valve controls water in a toilet tank, and in one form of operation has a hollow ball, mounted by a connecting rod to the valve. As the hollow ball rises with the water level, the valve closes until water flow is completely stopped.

Flood Level Rim: The top edge of a receptacle where water overflows.

Flushometer Valve: A device that discharges a predetermined quantity of water to fixtures for flushing purposes. It’s closed by direct water pressure.

Flush Valve: A device located at the bottom of the tank for flushing water.

Galvanic Corrosion: Corrosion caused by natural chemical interactions between different metals.

Galvanized Steel Piping: Steel water piping, coated with a zinc compound. The zinc on the outside acts as a sacrificial metal, slowing down the corrosion process.

Garbage Disposal Reset Button: A button on the bottom of the garbage disposal used to reset the overload device on the disposal. The overload device trips when the disposal becomes locked up, preventing motor damage and potential fire hazards.

GPM: GPM stands for gallons per minute. GPM is used when describing how much water a fixture uses to operate.

Hose Bibb: Water fitting to which a water hose is connected. It’s also referred to as a spigot or faucet. There are also internal hose bibs which are found in the laundry area for washing machine hook up.

Hub: The wide end of a fitting that allows insertion of a pipe to make a joint.

Hydrostatic Testing: A test that uses non-compressible liquid under pressure at a level equal to or greater than the maximum pressure that will be utilized when in use. The test can be used to find leaks.

Insanitary: Contrary to sanitary principles or injurious to health.

Interceptor: A device designed to separate and retain hazardous or undesirable matter from normal wastes, and permit normal sewage or liquid wastes to discharge into the drainage system by gravity.

Leader: An exterior drainage pipe used to convey stormwater from roof or gutter drains to the storm drain or other means of disposal.

Low-flow: Water fixture that produces a lower water flow at the outlet.

Main Drain: The slanting pipe in a crawl space or basement that carries wastes to a sewer or septic tank. It’s also called the building drain.

Main Vent: The principal artery of a venting system, to which vent branches may be connected.

Overflow: A drain used to prevent the overfilling of a fixture. An example is the small hole near the top of a bathroom sink which connects to the sink drain, preventing the basin from flooding.

PEX Tubing: A newer type of flexible piping, used to replace the potable water piping in a dwelling or building. PEX tubing uses hose barb connections and compression rings, and so it requires less labor to install. It installs easily around corners, omitting the need for the elbow fittings needed when installing other kinds of piping, including copper or galvanized piping.

PH: PH stands for potential of hydrogen. It’s a measurement used to determine acidity or alkalinity in a given substance.

Pneumatic: Types of devices that make use of compressed air, as in pressure tanks boosted by pumps.

Potable Water: Refers to drinking water that has no impurities present in amounts sufficient to cause disease or harmful physiological effects. It must conform in its bacteriological and chemical quality to the requirements of the Public Health Service drinking water standards or meet the regulations of the public health authority having jurisdiction.

Pressure and Temperature Relief Valve: Often referred to as P&T, this safety valve is installed on hot water storage tanks to limit temperature and pressure of the water.

P Trap: A trap or curved section of pipes that prevents sewer odors from escaping into the house. It has a vertical inlet and horizontal outlet and it’s required on all fixtures with a drain.

Pressure Gauge: A measuring device used to determine pressure in a piping system.

Pressure Tank: Part of an assembly that reserves water for use. The tank contains a bladder which puts pressure on the water in the tank so when a faucet or spigot is opened, the pressure will force the water through the piping. Through switches and gauges, the tank monitors the water pressure and starts the pump when pressure lowers to a predetermined level. When the valve closes, the pump continues until the water has reached the upper pressure limit.

Public Sewer: The common sewer which is directly controlled by public authority.

PVC: PVC stands for polyvinyl chloride and is a popular piping used in a myriad of plumbing and home capacities.

Relief Vent: An auxiliary vent that permits circulation of air in or between drainage and vent systems.

Riser: Supply pipes that run vertically from floor to floor.

Roughing In: Positioning and installing supply, drain, waste or vent pipes in walls and floors, without connecting fixtures while the walls and floors are unfinished.

Septic Tank: A watertight receptacle that receives the discharge of a house’s or building’s sanitary drain system or part thereof, which is designed and constructed so as to separate solid from the liquid, digest organic matter through a period of detention, and allow the liquids to discharge into the soil outside of the tank through a system of open-joint or perforated piping, or through a seepage pit.

Service Pipe: A pipe that delivers cold water to the house or building from a water main or well.

Sewerage System: A system including all piping, appurtenances and treatment facilities used for the collection and disposal of sewage, except plumbing inside and in connection with buildings served and the building drain.

Shut-Off Valve: A valve that cuts off water to one or more fixtures. It allows repairs without shutting off the supply system for the entire house.

Siphoning: Suction allowed by dropping water pressure that draws water or waste through the lines.

Snaking: A method of clearing blocked drains by pushing and twisting a drain-and-trap auger.

Soil Pipe: The pipe that directs the sewage of a house to the receiving sewer or building drain.

Soil Stack: A large vertical pipe that carries waste from fixture drains to the main drain.

Solder: Solder is the process and substance used to seal one metallic material to another.

Solvent Welding: The process of joining two things together by using a solvent, which softens the materials, then evaporates after adhering them.

Spigot: A commonly used term for a hose bib.

Storm Sewer: A sewer used to convey rain water, surface water, cooling water, or similar liquid waste.

Street Ell: An elbow joint with a hub on one end that is used to make an angled connection between pipe and a fitting with a hub.

Sump Pump: A pump that removes water from a collection pit.

Sweating: The process of connecting copper pipe and fittings with soldered joints.

Tapping In: The process of connecting new pipes to an existing plumbing line to serve a new fixture.

Tee: A widely used fitting that is shaped like a “T.”

Threaded Connections: Spiral ridges on the ends of pipes which are used to connect them.

Trap: A device that provides a liquid seal to prevent the emission of sewer gases, without materially affecting the flow of sewage or waste water.

Trunk Line: The main cold water supply pipe.

Union: A three piece fitting that joins two sections of pipe, which allows them to be disconnected without having to cut the pipe.

Vacuum Breaker: A device to prevent backflow or back siphonage, by means of an opening through which air may be drawn to relieve negative pressure.

Valve Dressing: The process of grinding a worn valve seat with a special tool to stop drips in compression faucets.

Vent Stack: A large vertical pipe that projects above the roof, extending from the soil stack, which vents sewer gases, thereby preventing gases from entering the living space.

Water Hammer: The loud thump of water that can be heard in a pipe when a valve or faucet is suddenly closed.

Water Service Pipe: A pipe from the water main or other sources of potable water supply that extends to the water-distributing system of the building served.

Water Supply System: A system consisting of the water service pipe, the water-distributing pipes, the necessary connecting pipes, fittings, control valves, and all appurtenances in or adjacent to the building or premises.

Wet Vent: A vent that receives discharge of waste other than from water closets.

Wye or Y: A Y-shaped fitting that joins three lengths of pipe in branch-like fashion.

Yoke Vent: A pipe that connects vertically from a soil or waste stack to a vent stack for the purpose of preventing pressure changes in the stacks.

This glossary of terms was compiled from the Int’l Association of Certified Home Inspectors, Angie’s List, Lowes and Everest Institute.

Photos courtesy of: geoffrey_whiteway