Plumbing and Drain Glossary

Acid Waste Piping: Drainage pipes made from acid-resistant material like polyvinylidene fluoride or glass, used in places such as printing presses, laboratories and hospitals to dispose of corrosive acidic waste.

Backwater Valve: A valve on a sewer line that stops sewage from reversing direction back into a building and contaminating water supply lines with fecal matter.

Ball Passage: A measurement unit of a toilet trapway that is determined by the size of ball that can fit through it. In most cases, a trapway is an eighth of an inch wider than the maximum size of ball that is able to pass through it.

Cesspool: An underground pit where sewage waste and grey water are deposited. It retains solid waste and allows liquids to drain into the soil.

City Sewer: An industrial-grade sewage and wastewater disposal system installed, maintained and operated by a municipality to treat and dispose of plumbing waste from commercial and residential buildings in that city or town.

Cleanout: A plug in a drainage line that can be removed to access the inside of the line and remove a blockage with drain cleaning tools.

Discharge Tube: An outlet tube that joins a disposal or sump pump to a drainage line.

Drain: A primary conduit through which wastewater and other debris can travel to a receptacle such as a septic tank, cesspool or storm water cistern, or be released into a sewer main.

Floor Drain: A drain opening set flush into the lowest point of the floor in an area like a shower or laundry room where water needs to be drained away from the floor surface.

French Drain: A channel that runs along the outside perimeter of a building and is covered with rocks, gravel or other loose material that allows rainwater to seep through to the drain channel and be disposed of away from the foundation of the building.

Hubless: A type of drainage pipe made from cast-iron with mechanical joints and neoprene gaskets. It is referred to as a hubless or "no-hub" because it doesn't have a bell-shaped hub on the end.

Liquid Waste: Wastewater or grey water from a plumbing fixture such as a sink, shower or bathtub that does not contain human or animal waste.

Plunger: A common household plumbing tool used to dislodge clogs from drains. The plunger forms a seal around the drain opening and creates suction that pulls the clog loose. Flat drains on floors, sinks, bathtubs and showers require a cup-shaped plunger, while toilets require a ball or bell-shaped plunger that can seal a toilet drain.

P-Trap: A curved pipe under a bathtub, shower or sink drain that remains filled with water, sealing off the line so gaseous odors can't move from the sewer line up and out of the fixture.

Sewage: A combination of human waste and wastewater that is carried through drain pipes to a septic tank or city sewer system so it can be treated with chemicals.

Sewer Line: A wastewater disposal conduit that allows wastewater and human waste to be carried out of a building and into a city sewer or septic tank.

Soil Stack: A large, vertical drainage line that connects to branch vents and carries wastewater into the building's sewage main.

Tailpiece: The short span of drain pipe that connects a plumbing fixture such as a sink to its P-trap.

Trenchless Sewer Repair or Replacement: The terms trenchless sewer repair or trenchless sewer replacement refer to several different methods of repairing or replacing sewer pipes that are buried underground without the need to dig a trench to access them. The two key methods of trenchless sewer line repair or replacement are pipe relining and hydraulic bursting.

Wastewater: Water that is no longer considered clean because it has been used for domestic, commercial or industrial purposes. It may or may not contain harmful contaminants.

Yoke Vent: A vent pipe that sits above a soil stack or vertical waste stack to prevent sudden pressure changes in the stack.

Plumbing Terms and Definitions

Access Panel: A hatch, door or removable panel in an interior wall that can be opened to access certain plumbing components such as drain stacks and shutoff valves in order to maintain or repair those components.

Aerator: A faucet component or attachment that mixes air with the water released from the faucet to reduce splashing.

Anode Rod: A sacrificial component of traditional, tank-style water heaters that consists of steel core wire wrapped in magnesium, zinc or aluminum. It absorbs corrosion to protect the metal lining of the water heater tank, and it must be replaced regularly as it wears out quickly.

Ballcock: A valve connected to a ball-shaped float in a toilet tank that controls the flow of water from the supply line into the tank.

Boiler: A closed hydronic heating system that provides radiant heat to a building by moving hot water through radiator pipes.

BTU (British Thermal Unit): A unit of measurement for thermal energy that represents the amount of heat necessary to increase the temperature of one pound of water by one degree Fahrenheit.

Cistern: A large container that is buried underground. It collects and stores rainwater for use in applications such as irrigation.

Compression Fitting: A connector piece that joins two pipes together and forms a seal with ferrules, sleeves, gaskets and nuts so there's no need to solder the pipes.

Dope: Plumbing lubricant that is applied to a threaded fitting to make it pressure tight and watertight.

Duo Valve: An outlet tube that connects a drain pipe to a disposal or sump pump.

Energy Star: A program that is operated jointly by the U.S. Department of Energy and the U.S. Environmental Protection Agency to encourage the conservation of energy and reduce the strain on energy resources. The program certifies products, buildings and services, including some plumbing components, that meet certain energy conservation standards.

Ferrule: A threaded pipe ring made from soft brass or copper. In plumbing, they are a component of compression fittings that make the connection watertight. Ferrules are sometimes referred to as compression ring bushings.

Flush Valve: Located at the bottom of the toilet tank, this valve or flapper opens when the toilet is flushed so water from the tank comes out of the rim holes into the toilet bowl.

Gasket: A ring, typically made of rubber, that forms a watertight seal between connecting flanges.

Green Plumbing: Practices or components in plumbing systems that conserve water or electricity, such as tankless water heaters and low-flow toilets.

Hard Water: Water with high concentrations of dissolved minerals such as calcium and magnesium. Hard water is generally potable, but can cause serious problems for plumbing systems because mineral deposits build up inside the lines and block the flow of water, causing pressurized clogs.

Hose Bibb: An outdoor or indoor fitting valve that attaches to a hose such as a washing machine supply line or a garden hose.

Hydraulic Bursting: A trenchless pipe replacement method in which a severely damaged, buried line is burst apart with hydraulics and a new line is threaded into the gap left behind in the soil, eliminating the need to dig a trench to access the line.

Inside Diameter (ID): The diameter of the inside of a pipe, not including the width of the pipe walls.

Litres Per Flush (LPF): A measurement unit that represents the total amount of water needed to complete a flush cycle for a urinal or toilet, expressed in gallons.

Litres Per Minute (LPM): A measurement unit that represents the rate of speed of water moving through a plumbing fixture or fitting, expressed in the number of gallons moving through the fitting or fixture in one minute at a given water pressure.

Main: The main pipe or plumbing line that connects exterior and interior plumbing systems. There are two mains in a typical domestic plumbing system: a sewer line that carries wastewater and human waste out of the building and into a city sewer or septic tank, and a water supply pipe that brings fresh, potable water into the building so it can be expelled from faucets and shower heads and accessed by water-related appliances such as dishwashers and laundry machines.

Maximum Acceptable Concentration (MAC): The maximum concentration of a potentially harmful contaminant like lead that is permitted in potable water, according to federal guidelines.

Non-Potable Water: Water that is not safe to drink, cook with, bathe in or use for other domestic purposes because it has been contaminated by toxic chemicals, fecal matter, parasites, bacteria or other harmful substances. Wastewater is non-potable, and raw water may or may not be non-potable.

NPT (National Pipe Thread): The most common type of standardized pipe threading in Canada and the United States.

Outside Diameter (OD): The entire diameter of a pipe starting from the outside edge, including the thickness of the pipe walls.

Ovality: A measure of the difference between the narrowest and widest outside diameters on a single piece of tubing or piping.

Peak Hour Demand: The amount of water used during the period of highest usage in a building, city or region. It is usually considered to be one-third of the total, overall demand for water in a 24-hour period of time.

Pipe Relining: A trenchless pipe repair method that involves fitting a cracked or otherwise damaged drain line with a flexible sleeve saturated in epoxy resin. An inflatable tube inside the sleeve pushes it up against the walls of the pipe and removed once the epoxy hardens and cures, leaving behind a watertight tube inside in the original pipe so there's no need to dig a trench to access the line.

Potable Water: Fresh water that is safe to drink, bathe in, cook with and use for other domestic purposes because it is not contaminated with toxic substances. Water can be treated with chemicals to make it potable, but raw water can also be potable if it has not come into contact with contaminants such as harmful bacteria or parasites.

Raw Water: Water from a natural source that has not been chemically treated and may or may not be potable.

Rough-In: A plumbing fixture such as a toilet or sink that has been put in place but is not yet connected to supply pipes and drainage lines.

Shutoff Valve: A valve on a water supply main or individual plumbing fixture that can be manually closed to block water supply to the whole system or a specific fixture when plumbing repair or maintenance is being carried out.

Supply Pipe: A pipe conduit that brings fresh, potable water into a building and to fixtures like showers, bathtubs, toilets and sinks, as well as appliances such as dishwashers.

Thread Pitch: A metric unit of measurement for pipe threads that represents the distance between individual threads.

TPI (Threads Per Inch): A measurement of the number of threads on a fitting, expressed as the number of threads running across one inch of the fitting.

ULF (Ultra-Low Flush): A type of toilet fixture that conserves water by only using six litres (1.6 gallons) of water per flush.

Volumetric Flow Rate: A measurement of the speed of water movement based on the volume of water that passes through a plumbing system during a given span of time. It is also called volume velocity.

Voral Tube: A flexible hose made of steel that connects a handheld shower head to the water supply line.

Water Hammer: Banging or thumping noises from pipes that occur due to a surge in pressure caused by water in motion coming to a sudden stop or reversing direction, forcing the pipes to vibrate and make noise. It is a symptom of a plumbing problem that needs to be addressed before it causes a leaky fitting or collapsed line.