Glossary of Terms

The Definition of Plumbing

Plumbing Glossary

ABS Aristocraft bristone styrine, a rigid black plastic pipe used for drain, waste, and vent lines.
Aerator A device screwed into the end of a faucet spout that mixes air into flowing water, and controls flow to reduce splashing. It sometimes contains a baffle to reduce flow to 2.5 gpm.
Air Lock Blockage in the flow of liquid, esp. on the suction side of a pump caused by an air bubble in the line.
Angle Stop A shutoff valve between the water pipes and a faucet. Its inlet connects to the water supply pipe in a wall, and its outlet angles up 90 degrees toward the faucet. These are usually used to shut off water to a fixture in case of an emergency repair rather than daily usage.
Anode Rod A sacrificial rod installed in a water heater that protects the tank from corrosion, helping to extend the life of the tank.
Anti-Siphon Preventive device for the backflow of liquid into a system. Used on sprinkler systems to prevent water from trickling back into the supply that is feeding it.
Back Flow Preventer A device to prevent water from traveling from one system back into any part of the main distribution system, usually by siphoning, esp. into a potable water supply. This is generally required for sprinkler systems, handheld showers, pullout faucet spouts, kitchen sprayers, etc.
Back Pressure Pressure that resists the flow of fluid in a piping system.
Backwater Valve Sewer line valve that prevents sewage from flowing back into the house.
Ball Check Valve A valve that uses a ball to seal against a seat to stop flow in one direction.
Ballcock The fill valve that controls the flow of water from the water supply line into a gravity-operated toilet tank. It is controlled by a float mechanism that floats in the tank water. When the toilet is flushed, the float drops and opens the ballcock, releasing water into the tank and/or bowl. As the water in the tank is restored, the float rises and shuts off the ballcock when the tank is full.
Basin Wrench A wrench with a long handle with jaws mounted on a swivel that allows the jaws to reach and handle nuts to fasten faucets to a previously installed sink.
Blowbag A drain-cleaning device consisting of a rubber bladder with a hose fitting on one end and a nozzle on the other. The device attaches to a water hose and is inserted into a clogged drainpipe. As water is introduced, it expands to grip the pipe, and releases pulsating bursts of water through the nozzle, forcing water through the pipe to clear the obstruction.
Branch Any part of a drain system other than the main, riser, or stack.
Branch Vent A vent connecting one or more individual vents with a vent stack.
BTU British Thermal Unit – A unit of heat energy required to raise the temperature of 1 lb. of water 1 degree Fahrenheit.
Catch Basin Large underground container, with a grate on the top, for collection of storm water run-off. It catches or collects dirt and other debris and prevents them from polluting streams and lakes.