Glossary of Plumbing Terms - The American Plumber

Plumbing Terms & Definitions

In this glossary you will find definitions to common plumbing terminology and other industry related terms to help you better understand the content on this website

A

ABS: A durable plastic material commonly employed for constructing drainage systems and ventilation channels within residential and commercial structures.
Absorption Field: An engineered underground system designed to safely disperse and filter the liquid waste emanating from septic tanks.
Access Panel: A removable section strategically positioned in walls or ceilings, facilitating convenient access for maintenance or repairs to plumbing fixtures and electrical components.
Activated Carbon: A highly porous and adsorbent substance derived from carbonaceous materials through a specialized heating process, utilized for the removal of contaminants such as chlorine, organic compounds, and radon from water supplies.
Adaptor: A connector that enables the joining of dissimilar pipe materials, allowing for a seamless transition between different plumbing systems.
Aerator: A device affixed to faucet outlets that introduces air into the water stream, reducing splashing and regulating water flow to conserve resources.
Air Admittance Valve: A specialized component that replaces traditional venting systems, allowing for the equalization of air pressure within plumbing lines while maintaining the integrity of fixture traps.
Angle Stop: A valve strategically positioned between water supply lines and faucets, designed to control and halt water flow when necessary, facilitating routine maintenance or emergency repairs.
Angular Discharge Tube: A specialized component that redirects the flow of water, altering its trajectory by approximately 90 degrees.
Anode Rod: A sacrificial metal rod installed within water heater tanks to mitigate corrosion, thereby extending the functional lifespan of the tank.
Anti-Scald Valve: A safety device integrated into plumbing systems to prevent the discharge of dangerously hot water, protecting users from potential scalding.
Anti-Siphon: A preventive mechanism employed in irrigation and sprinkler systems to prevent the backflow of water into the main supply line, ensuring the integrity and safety of the water source.

B

Back Pressure: The resistive force that opposes the desired flow of fluid within a piping network.
Backflow: The undesirable reverse flow of water from a system back into the main supply line, posing potential contamination risks.
Backflow Preventer: A safety device designed to prevent the backflow of water from a system into the main water distribution network, especially safeguarding potable water supplies from contamination. These are commonly required for irrigation systems, handheld showers, and other plumbing fixtures where backflow risks exist.
Backup: The undesirable overflow of a plumbing fixture, typically caused by a blockage or obstruction in the drainpipe.
Backwash: The process of reversing the flow of water through a filter or ion exchange medium, dislodging and flushing away accumulated particulates and contaminants that were removed during the normal filtration cycle.
Backwater Valve: A specialized valve installed in sewer lines to prevent the backflow of sewage into residential or commercial buildings.
Ballcock: The valve mechanism responsible for controlling the flow of water from the supply line into a gravity-operated toilet tank. It is regulated by a float that rises and falls with the water level, opening the valve to refill the tank after flushing and closing it when the desired level is reached.
Basin Wrench: A specialized wrench with an elongated handle and swiveling jaws, designed to access and tighten or loosen nuts used to secure faucets to pre-installed sinks.
Basket Strainer: A perforated, basket-shaped strainer installed in sink or shower drains, allowing water to pass through while capturing food particles, hair, and other debris, preventing them from entering and potentially clogging the sewage system.
Bidet: A plumbing fixture designed for personal hygiene, resembling a low-mounted sink or toilet, equipped with a water spray for cleansing the genital and anal areas.
Bleed: The process of removing excess air from a pipe, tube, or hose by opening a valve at the end or systematically forcing or suctioning the trapped air out.
Boiler: An enclosed vessel designed to heat water and convert it into steam for various applications, such as power generation or hot water supply.
Boiling Point: The temperature at which a liquid transitions into a gaseous state through the addition of heat energy.
BTU: British Thermal Unit – A unit of measurement representing the amount of heat energy required to raise the temperature of one pound of water by one degree Fahrenheit.
Burner: A component within a water heater responsible for producing the flame or heat source necessary to warm the water.

C

Catch Basin: An underground reservoir equipped with a surface grate, designed to collect and temporarily store stormwater runoff, trapping sediments and debris to prevent their introduction into nearby water bodies.
Centerset: A faucet design featuring a centralized spout flanked by two handles spaced precisely 4 inches apart, measured from their centers; this configuration also applies to single-handle faucets installed within 4-inch center-to-center mounting holes.
Check Valve: A specialized valve that permits fluid flow in only one direction within a pipe, effectively preventing backflow.
Chloramines: Disinfectant compounds formed through the chemical reaction between ammonia and chlorine, increasingly utilized by municipal water treatment facilities as an alternative to chlorine alone, without producing potentially carcinogenic trihalomethanes.
Chlorine: A widely employed disinfectant and oxidizing agent used in water treatment processes, available in gaseous, liquid (sodium hypochlorite), or solid (calcium hypochlorite) forms; however, its reaction with organic matter can lead to the formation of potentially carcinogenic trihalomethanes (THMs).
Circuit Vent: A vertical vent pipe within a building’s drainage system, designed to serve the last two trap connections on a horizontal drain line and connect them to the main vent stack.
Cleanout Plug: A removable plug or cap installed in traps or drain pipes, providing access for clearing obstructions or clogs.
Clevis Hanger: A type of pipe support featuring a swiveling yoke suspended from an adjustable vertical rod, secured to the pipe by a U-shaped metal strap (clevis) and bolted pin.
Closed System: A water supply system equipped with devices that prevent the expansion of heated water, such as check valves, backflow preventers, certain pressure-reducing valves, or water meters.
Closet: A term commonly used to refer to a toilet fixture.
Closet Auger: A flexible rod with a curved end, designed for accessing and clearing clogs within a toilet’s internal trap.
Closet Bend: A curved fitting installed directly below the toilet, connecting the closet flange to the toilet drain.
Closet Flange: An anchoring ring secured to the floor, to which the closet bend is attached; it features slots for inserting the closet bolts used to secure the toilet in place.
Cock: A faucet or valve used to regulate the flow of water, sometimes referred to as a ballcock.
Common Vent: A vertical vent within a building’s drainage system that serves multiple fixture branches on the same level.
Compression Fitting: A type of tubing or pipe connection that employs a nut and ferrule or sleeve to tightly compress and seal the joint without soldering, forming a secure grip on copper or plastic tubing; it can also refer to a flexible connector with a nut and gasket designed for direct attachment to SAE standard compression threads.
Compression Valve: A valve commonly used in water faucets, operated by raising or lowering a horizontal disk via a threaded stem.
CPVC: Chlorinated Polyvinyl Chloride – A rigid plastic pipe material approved for use in water supply systems where permitted by code.
Culvert: A pipe-like concrete structure installed beneath roadways to facilitate proper drainage and water flow.

D

Degree Rise: The temperature differential, or change, between the initial and final water temperatures during the heating process.
Desanco Fitting: An adapter employing compression technology to enable the connection of tubular brass fittings to PVC pipe systems.
Diaphragm: A flexible membrane within a valve assembly that flexes downward onto a rigid surface, regulating water flow from the supply lines and preventing debris accumulation inside the valve.
Dielectric: A material or substance that effectively insulates against the flow of direct electric current.
Dip Tube: A tube installed within a water heater tank, designed to direct incoming cold water to the bottom portion of the tank.
Discharge Tube: An outlet tube responsible for conveying the discharged water or waste from a disposer or sump pump into the drain line.
Dishwasher Tailpiece: A flanged adapter that connects the basket strainer to the drainpipe, incorporating an inlet for the dishwasher’s drainage hose.
Diverter: Specialized valves employed in showers, tubs, bidets, and sinks to selectively direct water flow to various outlets.
Drain Valve: A valve mechanism integrated into water heater systems to facilitate the draining and removal of stored water.
Dual Element Heater: An electric water heater equipped with two heating elements, one located in the upper portion and the other in the lower portion of the tank, for efficient water heating.
DWV: An abbreviation representing Drainage, Waste, and Vent, referring to copper or plastic tubing used for drain, waste, or venting applications within plumbing systems.

E

ECO: An acronym for Energy Cut Off, referring to a safety device integrated into water heaters that automatically shuts off power to prevent dangerously high water temperatures.
EF: The abbreviation for Energy Factor, a rating system that evaluates the overall efficiency of a water heater model based on factors such as recovery rate, thermal efficiency, standby heat loss, and energy input.
Efficiency: A quantitative measure, expressed as a percentage, that indicates a product’s ability to effectively utilize its input energy.
Elbow: A pipe fitting with two openings set at an angle, typically ranging from 22.5° to 90°, designed to change the direction of the pipe run.
Energy Guide Label: A mandatory label required by the Federal Trade Commission (FTC) for residential gas, electric, and oil-fired automatic storage water heaters, providing an estimated annual operating cost based on national average fuel prices, as well as a comparative efficiency rating against similar models.
Escutcheon: A decorative metal flange or trim piece installed beneath faucet handles to conceal the faucet stem and mounting hole in the fixture or wall, providing a finished appearance.
Expansion Tank: A specialized tank designed to accommodate and absorb excess pressure resulting from thermal expansion within a closed water system.

F

Fall/Flow: The precise slope or pitch applied to a pipe run to facilitate proper drainage and flow.
Female Fitting: A fitting designed to receive and connect with a pipe or another fitting, with the opposing component being inserted into its opening.
First Hour Delivery (Rating): A performance metric that combines the usable hot water volume stored in the tank with the water heater’s recovery capacity during the initial hour of operation.
Fixture: In plumbing systems, fixtures refer to the various devices and components that provide water supply and/or drainage, such as sinks, tubs, and toilets.
Flapper Valve: The component located at the bottom of a toilet tank that opens to allow water to flow from the tank into the bowl during a flush.
Float Ball: A buoyant ball connected to the ballcock mechanism inside the toilet tank, rising and falling with changing water levels to activate or shut off the ballcock as needed.
Floor Flange: A fitting designed to secure and connect a toilet to a floor drain.
Flow Control Valve: A device installed to regulate and reduce the water flow rate (measured in gallons per minute or GPM) to a particular plumbing fixture, such as limiting a showerhead to 2.5 GPM instead of 5 GPM, promoting water and energy conservation.
Flow Rate: A measurement quantifying the volume of water flowing through a system, typically expressed in gallons per minute (GPM) or gallons per hour (GPH).
Flue: A passageway or vent designed to allow the safe expulsion of combustion byproducts.
Flue Baffle: A component within a flue system that redirects, checks, or regulates the flow of combustion gases.
Flue Damper: A device installed in the flue to minimize heat loss through the venting system by restricting convective airflow.
Flushometer: A specialized valve mechanism installed in toilets that automatically meters and shuts off the water flow after a predetermined volume has been discharged.
Flushometer Tank System: A toilet flushing system that utilizes the pressure from the water supply to compress and forcefully discharge water for flushing, as opposed to relying on gravity-fed tanks.
Flux: A paste applied to copper pipes and fittings prior to soldering to facilitate the fusion process and prevent oxidation.
Foam Insulation: The insulating material surrounding the exterior surface of a water heater tank.
French Drain: A covered trench containing a layer of permeable material, such as fitted or loose stones, designed to facilitate drainage and water dispersal.

G

Galvanic Action: A phenomenon that occurs when two dissimilar metals are immersed in an electrolytic solution, creating an electrical potential between them; if the metals are in electrical contact, a current will flow, causing the metal acting as the anode to corrode and dissolve, while the cathode remains protected from corrosion.
Gate Diverter: The pop-up lever mechanism on a bathtub faucet that activates the diverter valve, redirecting water flow between the tub spout and showerhead.
Gate Valve: A valve designed to control and regulate the flow of fluid through a conduit, pipe, or tunnel.
Grain Capacity: A measurement used to quantify the amount of resin contained within a water softener system, typically expressed in cubic feet or increments of 1,000 grains, with 30,000 grains being equivalent to 1 cubic foot.
Gravity Operated Toilet: A toilet that relies solely on the natural downward force of water stored in the tank to provide the necessary pressure for flushing, without the aid of any additional mechanical or pressurized systems.
Gray Water: Wastewater generated from sinks, showers, and bathtubs, but excluding waste from toilet sources.

H

Head Loss: The reduction in water pressure measured at a specific point within a system, typically expressed in units of feet or pounds per square inch (PSI).
Heat Trap: A component designed to restrict and minimize heat loss through the water connections to a tank.
Horizontal Branch: The lateral drain pipes that run horizontally from plumbing fixtures to connect with the main waste stack within a building or underground.
Horizontal Run: The horizontal distance that a fluid travels within a pipe, measured from the point of entry to the point of exit.
Hose Bibb: An outdoor faucet or spigot, commonly used for connecting hoses and also for supplying washing machines.
House Trap: A U-shaped fitting with two adjacent cleanout plugs visible at floor level, installed when the main drain line runs beneath the floor.
Hubless (No-Hub): A type of cast iron drainage pipe that features neoprene gaskets and clamps instead of traditional hub connections.
Hydronic: A system designed for the forced circulation of hot water, typically for heating applications.
Hydrostatic Test: A testing method that involves subjecting a component or system to non-compressible liquid under pressure equal to or greater than the maximum operating pressure, such as in the testing of steam boilers.

I

ID: The internal dimension or measurement of a pipe’s cross-section, used as the standard for sizing and classification of pipes.
Indirect Wastes: Drain pipes specifically designed to carry and discharge graywater into plumbing fixtures like floor drains, rather than directly into the main waste system.
Instantaneous Water Heater: A compact water heating appliance that rapidly heats water on-demand as it flows through an internal heat exchanger coil, rather than storing hot water in a tank.

J

Jet: A strategically designed orifice or feature within a toilet that directs a forceful stream of water into the trapway, rapidly initiating the siphoning action required for an effective flush.
Johnni-bolts: The specific type of closet bolts utilized to securely mount and anchor toilet bowls onto the closet flange.
Junction Box: The designated utility area or enclosure where the incoming power supply is connected to provide electrical service to a water heater.

K

Kafer Fitting: A cast iron drainage pipe fitting featuring a threaded hub designed to enable secure connection and integration with existing cast iron pipe lines.
Knockout Plug: A removable test plug made of PVC material, commonly used in plumbing systems and installations.

L

Lavatory (Lav): A permanently installed sink or basin with running water and drainage capabilities, designed for personal hygiene and cleansing purposes. It is commonly found in restrooms or bathrooms.
Leach Field: A strategically designed area of porous soil through which the perforated leach lines from a septic tank disperse and filter the treated waste effluent.
Leader: A pipe or conduit specifically intended to channel and convey rainwater from a building’s roof or gutters to either the ground or a sewer system.
Lock Nut: A specialized nut that is inserted and secured within one pipe section, allowing it to be threaded onto an adjoining pipe section to create a secure and watertight connection between the two.

M

Main: The principal and largest pipe or conduit within a water supply or drainage system, to which all smaller branch lines connect and feed into. In drainage systems, it is referred to as the Main Vent.
Male Threads: External threads found on the outer surface of pipes and fittings, designed to connect with female-threaded components.
Malleable Fittings: Pipe fittings constructed from a soft, pliable metal that can be easily formed or shaped.
Manifold: A specialized fitting that serves as a distribution point, allowing multiple branch lines to connect to and receive flow from the main line.
Micron Rating: A rating system used to indicate the maximum particle size that a filter or filter medium can effectively remove from a fluid, specified as an absolute rather than nominal value.
Mixing Valve: A valve designed to blend hot water from the water heater with cold water to achieve a desired delivery temperature.
Multi-Stage Pump: A pump containing more than one impeller, providing increased pressure and flow capabilities compared to single-stage pumps.

N

Natural Gas: A gaseous fuel supplied through a utility’s distribution network and utilized as the energy source for gas-fired water heaters.
Net Usable BTU: The portion of a fuel’s total heat energy that is effectively transferred and absorbed by the water within a water heater.
Nipple: A short length of pipe installed to bridge the gap between two couplings or fittings, facilitating their connection.
No-Hub Connector: A specialized connector used with hubless cast iron pipes, consisting of a rubber sleeve secured by a stainless steel band and hose clamps. A variation employs a neoprene sleeve with two adjustable steel bands, enabling the connection of dissimilar materials, such as joining new plastic pipes to existing cast iron drain lines.

O

O-Ring: A circular rubber gasket designed to create a watertight seal, commonly used around valve stems and other plumbing components.
OD: An abbreviation for Outside Diameter, referring to the external dimensions or measurements of a pipe or tubing.
Oakum: A loosely woven rope made of hemp that has been treated with oil or waterproofing agents, used for caulking and sealing joints in bell-and-spigot pipe fittings.
One-Piece Toilet: A toilet unit where the tank and bowl are constructed as a single, seamless vitreous china fixture, typically resulting in a lower overall profile compared to two-piece toilets.
Operating Cost: The expenditure associated with running and operating a water heater over a specified period of time.
Outlet Sewer: The section of piping within a septic system that connects the septic tank to the drainage field, facilitating the discharge of treated effluent.

P

Packing: Fibrous material used in faucet assemblies to create a tight seal and prevent leaks around the stem.
Packing Nut: A nut designed to secure the faucet stem in position and compress the packing material, ensuring a proper seal.
Parts Per Million (ppm): A common unit used to express the concentration of substances in water or wastewater analyses, indicating the number of parts by weight per million parts of the solvent. In dilute aqueous solutions, 1 ppm is approximately equal to 1 milligram per liter. 17.1 ppm is equivalent to 1 grain per US gallon.
PB: The abbreviation for Polybutylene, a flexible plastic tubing material approved for use in water supply systems where permitted by code.
Peak Hour Demand: The time period during which the demand for hot water is at its highest level.
Peak Load Period: The duration of the day when the system experiences its greatest demand for water or energy.
pH: An abbreviation for “potential Hydrogen,” a measure of the hydrogen ion concentration in water, indicating its acidity or alkalinity on a scale of 0 to 14, with values below 7 denoting acidity and above 7 denoting alkalinity.
Pilot: A small auxiliary burner used to ignite the main burner in a water heater or other appliance.
Pipe Dope: A slang term for pipe-joint compound, a substance applied to threaded pipe fittings to create a watertight seal.
Pitch: The downward slope or gradient of a drain pipe, designed to facilitate proper water flow in the desired direction.
Plumb: Precisely vertical or perpendicular to a horizontal plane. It can also refer to the act of testing for or establishing a vertical alignment, or to the performance of plumbing work.
Plumber’s Putty: A pliable putty material used to seal joints between drain components and fixture surfaces.
Plumbing Tree: A prefabricated assembly consisting of pre-configured drain, waste, vent, and supply lines.
Plunger: A tool with a rubber cup or head, used to create suction within a drain line or toilet to dislodge and clear clogs.
Point Of Use Water Heater: A compact water heater designed for localized or remote applications, providing hot water at the point of use.
Pop-Up Drain: A type of drain assembly commonly found in lavatories and bathtubs, featuring a pop-up stopper that closes to retain water when the lift rod or overflow plate lever is engaged.
Port: An opening or orifice in a burner head through which gas or an air-gas mixture is discharged for ignition.
Positive Displacement Pump: Commonly referred to as a PD pump, a type of pump in which the capacity is determined by the pump speed, while the maximum head is determined by the available horsepower and casing strength. Examples include gear, sliding vane, progressive cavity, and lobe pumps.
Pressure Balance Valve: A shower mixing valve designed to automatically maintain a balanced ratio between the incoming hot and cold water supplies, instantly compensating for fluctuations in pressure to keep the temperature constant, though outlet pressure may drop. Also known as an anti-scald valve.
Pressure Reducing Valve: A valve that automatically reduces incoming water pressure to a predetermined, lower value at its outlet under static cold water conditions.
Pressure Tank: A device used in well systems to maintain and regulate water pressure for distribution.
Pressure Tubing: Tubing manufactured to stricter tolerances than standard pipe, designed to handle elevated pressures, temperatures, or both, and used for conducting fluids under such conditions.
PVC: An abbreviation for Polyvinyl Chloride, a rigid white or cream-colored plastic pipe material approved for use in non-pressurized systems such as drainage, waste, and venting applications.

Q

Quick Connect: A specialized fitting designed for rapid and efficient attachment to a line or hose. Quick connect fittings are often one-piece components that can be forcefully pushed onto the end of a hose and securely locked into place.

R

Rated Storage Volume: The specified quantity or capacity of water, expressed in gallons, that can be stored within a tank.
Reamer: A grinding tool used to level or remove burrs from valve seats in faucets, ensuring a proper fit for the valve stem.
Recovery (GPH): The rate at which a water heater can produce hot water, expressed in gallons per hour.
Reducer: A fitting designed to connect pipes of different diameters, facilitating a smooth transition between the two sizes.
Reserve Capacity: The additional grain capacity allocated as a reserve in a water softener system, ensuring the continued supply of softened water until the next scheduled regeneration cycle.
Return Circulation System: A system that recirculates tempered water from or near the point of use, eliminating waste from long runs and effectively increasing the overall storage capacity.
Revent: A pipe installed specifically to provide venting for a fixture trap, connecting to the main vent system above the fixture.
Reverse Osmosis: A water treatment process that involves forcing water through a semi-permeable membrane to remove impurities, resulting in purified water.
Reverse Trap Water Closet: A toilet design featuring a siphonic trapway at the rear of the bowl, along with an integrated flushing rim and jet.
RF: An abbreviation for Recovery Factor, a rating based on the efficiency of a water heater, determined by the amount of energy input required to raise the temperature of one gallon of water by one degree Fahrenheit.
Rigid Pipe: A type of pipe designed to transmit the load from the surrounding backfill material to the foundation beneath, requiring support along the bottom portion of the pipe.
Rim Holes: A series of small holes located along the underside of a toilet rim, encircling the bowl’s circumference. These holes allow incoming water to flow down and create a rinsing effect, washing over the entire inner surface of the bowl during a flush.
Riser: A vertical metal or plastic tube or assembly that connects a faucet to the water supply stop valve, typically made of copper. Corrugated metal flex risers are designed to facilitate bending. The term can also refer to a supply line that rises from one story to the next.
Rough-In: The initial installation of drain, waste, vent, and supply lines within a structure, positioned at the proposed locations of the future plumbing fixtures.
Rough-In Dimensions: The specified distance from a finished wall or floor to the center of the waste or supply opening, or mounting holes, on a plumbing fixture.
Run: A complete or secondary section of pipe that extends from the supply source to a fixture or from a drain to the main stack.

S

Saddle Valve: A valve mounted onto an existing pipe run using a clamping device or saddle fitting, providing a tap point to quickly connect and supply water to low-demand fixtures or devices.
Safety Shut Off Valve: A safety device installed on gas appliances that automatically shuts off the gas supply to prevent hazardous situations. A flame failure safety shut off activates when the pilot flame is extinguished, while a 100% shut off completely cuts off gas to both the main and pilot burners.
Sanitary Fitting: A type of fitting designed for use in drain, waste, and vent systems, allowing solid waste materials to pass through without causing clogs or obstructions.
Sanitary Sewer: The main drain line that carries wastewater away from a building and into either a municipal sewer system or a private septic tank.
Self-Rimming Sink: A sink design that features a built-in lip or ledge made of the same material as the sink basin, eliminating the need for a separate metal rim and supporting the sink within the vanity top or countertop.
Shroud: A color-matched component installed beneath a wall-mounted lavatory, concealing the drain outlet for aesthetic purposes.
Siphon-Vortex Water Closet: A toilet design featuring a trapway at the rear of the bowl, an integrated flushing rim, and a water supply system that may or may not include a jet, but does not directly feed into the trap.
Sleeve: A pipe section installed through a wall, allowing another pipe to be inserted and passed through it.
Slip Joint: A type of pipe connection made using compression fittings.
Soil Stack: The largest vertical drain line within a building, to which all branch waste lines connect, carrying solid and liquid waste to the main sewer line.
Solder: A low-melting-point metal alloy used to create fused joints between metal components. The act of melting and applying solder to join metal pieces is also referred to as soldering.
Stack: The primary vertical pipe or main within a drain, waste, and vent system, extending through one or more stories of a building.
Stand Pipe: An open vertical pipe that receives wastewater discharge from washing machines. It can also refer to a vertical pipe supplying water to a fire sprinkler system, or a tall vertical pipe into which water is pumped to maintain a desired pressure within a water supply system.
Static Lift: The vertical distance between the source water level and the discharge water level in a pump installation.
Stop Valve: A shutoff valve typically installed beneath sinks and toilets, allowing the water supply to be isolated and cut off for a specific fixture without affecting the water supply to other fixtures.
Straight Cross: A fitting designed to connect four pipes of the same diameter at right angles.
Sump: A pit or chamber designed to collect, store, or drain water, and provide a reservoir from which a pump can draw water.
Sweating: A slang term referring to the process of soldering metal components together. It can also describe the formation of condensation on the exterior surfaces of pipes or toilet tanks.

T

T & P Valve: An abbreviation for Temperature & Pressure Relief Valve, a critical safety device designed to expel excessive pressure or temperature from within a tank to prevent potential hazards.
Tail Pipe: An additional pipe section installed below the jet assembly in a weak well application.
Tailpiece: The section of pipe that connects a plumbing fixture’s outlet to the trap.
Tank: The reservoir component of a toilet fixture that stores the flush water. In a conventional toilet, the ballcock, flush valve, and trip lever are installed within the tank, with a lid covering the top opening.
Tank Cross: A double-tee shaped fitting installed between a shallow well pump and the bladder tank, featuring integrated valve and gauge fittings, as well as an outlet for a pressure relief valve.
Tankless Water Heater: Also known as instantaneous or point-of-use water heaters, these compact units heat water on-demand as it flows through, rather than storing hot water in a tank.
Tap Tee: A cast iron tee fitting with a threaded female side inlet, designed for tapping into existing lines.
Tee: A T-shaped pipe fitting with three openings, used for creating branch lines or diversions within a piping system.
Temperature Rise: Also referred to as Delta “T”, it represents the number of degrees Fahrenheit that incoming cold water must be heated to reach the desired hot water temperature.
Thermal Expansion: The phenomenon whereby water, a non-compressible liquid, increases in volume when heated.
Thermocouple: A small electric generator that creates a millivoltage flow of electrons between a hot junction (typically 1200°F) and a cold junction (around 600°F).
Thermostatic Valve: A pressure-balancing shower mixing valve equipped with automatic temperature control. When temperature or pressure fluctuations occur at the water inlets, a thermal actuator adjusts the hot and cold water ratio to maintain the original temperature setting.
Trap: A curved section within a drain line that creates a water seal, preventing sewer gases from escaping into the atmosphere. All plumbing fixtures with drains must have a “P” trap installed, except for toilets, which have an “S” trap.
Trap Arm: The portion of a drainage trap that connects to the waste line.
Trap Dip: The U-shaped bend or curvature within a drainage trap.
Trap Primer: A small feeder line that connects the cold water supply directly to a drainage trap, releasing a small amount of water into the trap to maintain the water seal in case it evaporates.
Trap Seal: The depth or height of water remaining in a toilet bowl when at rest, providing a water seal that prevents sewer gases from entering the home. It is measured from the top of the dam down to the inlet of the trapway, and is also referred to as the deep seal.
Trapway: The channel within a toilet that connects the bowl to the waste outlet, facilitating the siphonic action during flushing. The trapway is measured by the largest diameter ball that can pass through it, and is also called the passageway.
Trip Lever: The flush handle and actuating arm mechanism located on a toilet tank, or the lever used to open and close the drain on a bathtub waste and overflow.
Turbulent Flow: A fluid flow characterized by erratic variations in velocity magnitude and direction at a given point, exhibiting chaotic and irregular patterns.

U

UL: An abbreviation for Underwriters Laboratories, a renowned independent safety certification organization that tests and certifies a wide range of products, materials, and systems.
Uni-flex: A one-piece combination component that integrates both a supply stop valve and a riser pipe, providing a streamlined and efficient water supply solution.
Union: A three-piece pipe fitting that allows for the connection and disconnection of two sections of pipe without the need for cutting, primarily used with steel pipe installations, but never employed in drain, waste, and vent (DWV) systems.
Usable Storage: The percentage of hot water that can be drawn from a tank before the temperature drops below the threshold at which it is no longer considered adequately hot for use.

V

Vacuum Breaker: A device designed to prevent backflow by introducing atmospheric air into a system, breaking any vacuum or siphoning effect that could potentially cause contaminated water to be drawn back into the potable water supply.
Vacuum Relief Valve (Anti-Siphon): A recommended safety component for installation on side-inlet (bottom) cold water heater connections, preventing internal vacuum conditions that could lead to system drainage through back-siphonage, and mitigating potential issues such as burned-out heating elements or collapsed tanks.
Valve Seat: The stationary component of a valve assembly against which the movable valve element seals or seats, halting water flow when they make contact.
Vent: A pipe that introduces air into a drain system, balancing the air pressure to prevent the siphoning or loss of water seals within fixture traps.
Vent Header: A vent pipe that multiple individual vents connect into, collectively channeling air flow to the main vent stack and out of the building.
Vent Stack: The uppermost section of the soil stack, extending above the highest plumbing fixture, through which sewer gases and odors are vented to the exterior.
Vent System: A network of pipes installed to facilitate the circulation of air within a drainage system, protecting trap seals from siphonage and back-pressure effects.
Venturi: A short, constricted tube or passage with a tapered center section that causes an increase in fluid velocity and a corresponding decrease in pressure, creating a suction effect that can be utilized in vacuum pumps or other applications.
Viscosity: A measure of a fluid’s resistance to flow, resulting from internal frictional forces between molecules, which tends to increase as the fluid’s temperature decreases.
Vitreous China: A ceramic material fired at high temperatures to create a non-porous body, with exposed surfaces coated in a fused ceramic glaze, commonly used in the manufacture of bathroom fixtures such as toilets, bidets, and lavatories.

W

Washdown Water Closet: A toilet design featuring a siphon trapway located at the front of the bowl, along with an integrated flushing rim.
Waste Arm: A drain extension pipe, commonly used to extend a sink drain into a wall cavity.
Waste & Overflow: A bathtub drain assembly consisting of an overflow outlet at the top to remove excess water during filling, and a main drain at the bottom for draining the tub.
Water Consumption: The quantity of water used within a household, measured in U.S. gallon increments. This figure can be determined by reviewing past water utility bills, or if unavailable, estimated at an average of 75 gallons per day per person, plus an additional 75 gallons per day for combined automatic washer and dishwasher usage.
Water Hardness: A measure of the calcium and magnesium carbonate and sulfide content in water, expressed in grains per gallon or parts per million.
Waterway Fitting: A fitting with an internal channel or passageway that allows water to flow through, connecting the water heater to the inlet and outlet lines.
Wet Vent: A type of vent pipe that serves the dual purpose of venting and draining wastewater.
Widespread: A bathroom lavatory faucet design featuring separate spout and handle components, with handles typically spaced 8 inches apart, measured from center to center.
WYE: A Y-shaped pipe fitting with three openings, used to create branch lines or diversions within a piping system.

Y

Yearly Cost: The total operational expense incurred over the course of a year for running and maintaining a water heater.
Yoke: A typically brass casting that houses both the hot and cold water valves, as well as the mixing chamber, facilitating the blending of water streams. It can also refer to an assembly constructed from copper or other metals that serves the same function.
Yoke Vent: A vent pipe that extends upward from a soil or waste stack, connecting to a vent stack with the purpose of preventing pressure fluctuations within the stacks.