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Plumbing Terminology
Extensive Online Plumbing Dictionary

Click on any letter of the term you would like to find

"S" Trap:
Trap design which routes drainage vertically down through the floor to connect with the drainage waste vent (DWV).

Saddle Tee:
Fitting that taps into the side of a pipe, used to make quick connection to an existing line.

Saddle Valve:
A valve mounted on a pipe run by a clamping device, or saddle tee to provide a water supply for a low-demand device.

Society of Automotive Engineers standard. a thread size used on nuts and bolts but not pipe connections.

Safe Drinking Water Act:
An amendment to the Public Health Service Act, which was passed in 1976 to protect public health by establishing uniform drinking water standards for the nation. In 1986 SDWA Amendments were passed that mandated the EPA establish standards for 83 drinking water contaminants by 1992 and identify an additional 25 contaminants for regulation every 3 years thereafter.

Safety Shutoff Valve :
A device on a gas appliance that shuts off the gas supply to prevent a hazardous situation. A flame safety shutoff operates when the actuating flame becomes extinguished.

Sag Pipe:
A section of a sewer line that is placed deeper in the ground than normal in order to pass under utility piping, waterways, rail lines, highways, or other obstacles. The sewer line is raised again after passing under the obstacle.

Sanitary Fitting:
Fitting that joins the assorted pipes in a drain, waste, and vent system, designed to allow solid material to pass through without clogging.

Sanitary Sewer:
House drain that carries wastewater away from the house to a sewer system or septic tank.

The process in which a fatty acid is neutralized with an alkali or base to form a soap.

Scald Guard:
Scalr-Guard valves are designed to prevent extreme water temperature changes through pressure balance technology. When there is a drop in hot or cold water pressure, the scald-guard valve shifts back and forth behind the shower handle to compensate for the sudden change. This valve maintains a constant water temperature to help give you and your family a safe and enjoyable bathing experience.

A thin coating or layer, usually calcium on the bottom of a tank or interior parts that may prevent heat transfer.

Numbers assigned to different wall thicknesses of pipe (e.g. sch 40).

Screwdriver Stop:
Used with tub/shower faucets.

Scullery Sink:
Type of sink used in commercial or institutional kitchens.

Drain, normally located on a roof or deck that allows rain water to drain off.

Sealed Combustion:
Sealing of combustion chamber to prevent spillage of combustion products.

Sealed Combustion Heater:
A heater which pulls combustion air from outside the structure and vents combustion by-products to the outside.

Sealed Overflow:
No overflow. Sink or tub made without an overflow. Overflow sealed over by factory.

Seal-Off Fitting:
Fitting which prevents gas leakage from moving from one section of pipe to another.

Seamless Pipe:
Pipe with no weld in the circumference.

Secondary Air:
The remaining air needed for complete combustion besides primary air. This is the air surrounding the flames outside the burner ports.

The substance that settles on the bottom of a water tank. Also known as lime.

Self-Closing Faucet:
Commercial lavatory faucet that flows water for a set time after the handle is pushed or turned.

Self-Rimming Sink:
A style of bathroom lavatory or kitchen sink with a rolled and finished edge, or rim. The fixture installs on top of a counter without the need for a metal sink rim.

Septic Tank:
A tank used to detain domestic wastes to allow the settling of solids prior to distribution. Septic tanks are used when a sewer line is not available to carry them to a treatment plant.

Sequestering Agent:
A chemical compound sometimes fed into water to tie up undesirable ions, keep the in solution, and reduce their effects. For example, polyphosphate can sequester hardness and prevent reactions with soap.

Serial/Model/Rating Plate:
A permanent information plate attached to major home appliances. The plate includes product model and serial numbers, plus information about wattage or BTU requirements.

Series System:
System where a primary heater preheats water to a given desired general purpose temperature and feeds into another heater.

Service Entrance:
Pipe connecting the water company piping to the water meter.

Service Pressure:
The range of pressure in the pressure tank during the pumping cycle, usually expressed in pounds per square in gauge (PSIG).

Service Sink:
Deep fixed basin, usually supplied with hot and cold water, which is used for rinsing of mops, disposal of cleaning water, or washing clothes and other household items.

Service Sink Faucet:
Commercial grade faucet used on a service or utility sink.

Service Tee:
Tee fitting with male threads on one run opening and female threads on the other two.

Pumps: vertical distance in feet from the top of the well to the top of the pump.

Sewer Gas:
Gases, esp. methane, which may be combustible and poisonous from the decay of organic materials in the sewer system.

Shallow Well:
A well with a pumping head of 25 feet or less, permitting use of a suction pump.

Shower Arm:
Shower trim component that delivers water to the showerhead. Usually 1/2" NPT. The shower arm connects showerhead and water supply line behind a finished wall of the shower enclosure.

Shower Body:
Also referred to as the "valve body" shower ell inlet.

Shower Ell:
Plumbing elbow into which threads the shower arm. It is secured to the wall framing. The vertical water supply pipe from the bath/shower valve connects to the shower ell inlet.

Shower Panel:
Shower panel is a separate panel that mounts on a shower wall that includes a valve, showerhead, handshower, and body sprays. This is a quick and easy way to add these functions to your shower without tearing out the wall.

Shower Receptor:
A one-piece base (floor) unit used as a shower, for example, to catch water and direct it to a center drain.

Shower Supply Elbow:
Plumbing elbow into which threads the shower arm. It is secured to the wall framing. The vertical water supply pipe from the bath/shower valve connect to the shower ell inlet.

Decide that delivers water in a showering space. It may have an adjustable spray feature and a valve for regulating the flow of water from the shower.

Color-matched component under a wall-mount lavatory that covers the drain outlet for aesthetic purposes.

Shutoff Valve:
Most commonly refers to angle stops installed under sinks and toilets, but also valves installed on branch lines and alongside the meter.

Side Cutter:
A heavy duty auger tip for large diameter pipes.

Sight Hole:
Generally a window on oil-fired products that allow the viewing of burner and flame patterns.

An outdoor faucet furnished with hose threads on the spout. Also used to supply washing machines. Also known as a "hose bibb".

An ejector pump container usually 18" x 30" for single family homes.

Single Threshold:
Type of shower base used in a three wall installation with the threshold being the side with the door.

Single Basin Sink:
Term used to describe a sink comprised of a single compartment.

Single Control Faucet:
Type of faucet that has one handle to control both water temperature and water volume.

Single Hole Sink:
One hole drilling positioned in the center of a sink or lavatory faucet ledge providing for installation of a single control faucet.

Single Hole Faucet:
Faucet which installs into a single fixture hole.

Single Threshold:
Type of shower base used in a three wall installation with the threshold being the side of the door.

Sink (Kitchen):
Any variety of fixtures used as a method of personal expression for entertaining, food preparation, and dish washing. May contain one or more basins, which may be of varying dimensions.

A pipe connecting two canals. A tube or pipe through which water flows over a high point by gravity.

The suction or pulling effect that takes place in the trapway of a toilet as it is filled with outgoing water and waste.

Siphon Break:
The point in a toilet flush cycle when air is re-introduced into the trapway, breaking the siphonic action. This is characterized by the deep gurgling sound heard at the end of a flush.

Siphon Jet Toilet:
A toilet having a trapway at the rear of the bowl and integral flushing rim, and minimum dimensions of 5" x 4" water spot and 1-1/2" ball pass. Similar to reverse trap flushing, but more efficient.

Siphon Vortex Toilet:
A toilet having a trapway at the rear of the bowl integral flushing rim and a water supply system with or without a jet, which does not feed directly into the trap.

Siphon Wash Closet:
A toilet having a trapway at the rear of the bowl and integral flushing rim, and minimum dimensions of 5" x 4" water spot and 1-1/2" ball pass.

Pipe which is passed through a wall for the purpose of inserting another pipe through it.

Slide Bar:
Type of shower component designed for the attachment of a handshower. The mounting bracket can be adjusted at different heights to accommodate individual preference.

Sliding Inner Door:
A door that slides along the combustion chamber radius for easy access to the burner and pilot.

Sliding Panels:
The moving panels in a bypass door.

Slip Gasket:
Elastomer gasket, usable with a hub and spigot pipe because it has a tapered cross section.

Slip Joint:
A connection made with compression fittings.

Seamless pipe.

Satin Nickel.

Term plumbers use after a mechanical metal cable has been used to clear a stoppage in a drain line. The metal cable is referred to as a snake, therefore the drain has been "snaked".

Snake Oil:
Lubricant used to keep metal cables from rusting or corroding after being used in a drain line.

Soap/Lotion Dispenser:
Accessory that holds liquid soap or lotion. May be installed in a predrilled sink hole or through a 1" max thickness countertop.

Synthetic Organic Chemicals - Manmade chemicals containing carbon and have been linked to chronic health affects.

Soda Ash:
The common name for sodium carbonate, Na2CO3 a chemical compound sometimes used in soap and detergents to neutralize acid water.

Soft Flame:
A flame partially deprived of primary air such that the combustion zone is extended and the inner cone of the flame is ill-defined.

Soft Water:
Water that has a low calcium and magnesium content.

Soil Cutter:
A device used to cut No Hub pipe, consisting of a handle and a cutting chain, similar to a chain wrench in appearance.

Soil Pipe:
A sewer pipe for carrying off waste from toilets.

Soil Stack:
Largest vertical drain line to which all branch waste lines connect. This line carries waste to the sewer line.

A metal alloy that is melted to create a fused joint between metal pieces. Also the act of melting solder into the joint.

A coil of wire in the form of a cylinder that, when carrying a current, resembles a bar magnet.

The substance which is dissolved in and by a solvent. Dissolved solids, such as the minerals found in water, are solutes.

Solvent Weld:
Any of the types of PVC pipe and fittings that are fastened together with solvent-based cement.

A black substance, mostly consisting of small particles of carbon, which can result from incomplete combustion and appear as smoke.

Spark Ignition:
Intermittent ignition devices that utilizes a spark to light a flame.

Spark Test:
A test procedure to evaluate the integrity of the glass lining.

Specific Gravity:
The ratio of the weight of a specific volume of a substance compared to the weight of the same volume of pure water at 4°C.

Specific Heat:
Amount of heat required to raise the temperature of a kilogram of a substance one degree Celsius.

One abbreviation for "spigot". Other abbreviations include, Sp and Spig. See definition of spigot below

SPG x Hub:
Spigot on one end of a fitting or pipe and Hub on the other end. See definition of "hub"

Term used with cast-iron, PVC, CPVC and ABS pipe. Cast-Iron; The plain end of a cast-iron pipe. The spigot is inserted into the bell end of the next pipe to make a water tight joint. PVC, CPVC or ABS; A male end of a fitting the same size as the pipe that is inserted into the slip (hub) end of a fitting.

Spigot Soil Adapter:
Hub adapter to connect PVC with soil pipe.

Spline adapter:
Device sometimes required to form a mating connection between the splines of a valve stem and the splines inside a faucet handle.

Delivers water from the faucet valve to the sink, lavatory or bath.

Spout Height:
Vertical measurement from the base of the faucet to the tallest point of the spout reach.

Spout Reach:
Horizontal measurement from the center of the spout/shank to the center of the aerator.

Specialized reproductive bodies or resting cells that resist adverse conditions which would readily destroy the parent organism.

A threaded opening on the water heater tank. Also a tool for digging having characteristics of a shade and chisel.

An abbreviation normally used for PVC or CPVC fittings, describing a fitting with a spigot end (male) on one side and a slip (female) connector on the other side. The spigot end is the same size as the pipe that glues into a slip fitting. The slip fitting is a normal hub end that fits over pipe. Note: spigot and slip connections are non-threaded; either glue in or glue on.

See SPxS definition above.

The vertical main in the drain, waste, and vent system, extending one or more stories.

The ability of hot water to form layers of different temperatures in the tank stratification.

Stainless Steel Sinks:
Material used in the manufacture of kitchen sinks. Sheet metal is drawn into a shape that has a degree of depth. Additional press operations include punching of faucet holes and forming of fixture rims.

Stand Pipe:
Open vertical pipe that receives water from a washing machine. Also the vertical pipe run supplying water to a fire sprinkler system; also large vertical pipe into which water is pumped in order to produce a desired pressure; a high vertical pipe or reservoir that is used to secure a uniform pressure in a water-supply system.

Static Discharge Head:
The vertical distance from the pump to the highest outlet in the water system Stand By Loss. The amount of heat lost while a unit is in stand by mode.

Static Lift:
The vertical distance between source and discharge water levels in a pump installation.

Static Pressure:
The pressure at the valve inlet that is exerted under a "no flow" condition.

Static Water Level:
The undisturbed level of water in the well before pumping.


Part of the faucet that holds the handle on one end and the water on the other.

A galvanized bushing used to strengthen tubing to fit in a leadpak coupling.

Stillson Wrench:
Pipe Wrench.

The shutoff valve under sinks and toilets. Allows water supply to be cut off to one fixture without affecting the water supply to the entire house or building.

Stop and Drain Fitting:
Plug-type valve used to tap into a water main to control the flow to a branch line, which has a side opening to shut off the water and allow it to drain out so the pipe won't freeze.

Stop Valve:
Same as a stop.

Storage Tank:
A tank used to hold a specific volume of water.

Storm Drain:
Drain used to receive and convey rain water, surface water, and ground water away from buildings.

Straight Cross:
Fitting that connects four pipes of the same diameter.

Straight Pipe Threads:
A special kind of straight thread used only on iron pipe, toilet and faucet fittings. A cone sealer gasket is usually included because straight threads will not form a complete seal without a gasket of some kind.

Straight Stop:
An emergency stop valve that is usually installed before the water supply line to toilet and faucets. Similar to angle stops but the line does not change direction.

Sink drain fitting consisting of a strainer body attached to the drain opening and a removable basket. Also called a duo strainer.

Strainer Pot:
A housing on the influent side of a pump that serves as a priming chamber and a receptacle for the strainer basket.

Strap Wrench:
Tool with metal body and heavy cloth or metal mesh belt used for turning pipe.

Street Ell:
A 90° elbow joint with a hub on one end and male threads on the other. Used to make an angled connection between pipe or tubing and a fitting with a hub.

Short lengths of pipe installed during rough-in to which fixtures and drains will eventually be installed.

Stud Guard:
Short band of metal attached to wall studs to prevent nails from penetrating and damaging pipes.

Stuffing Box:
that portion of the pump that held the packing and now holds the mechanical seal.

The distance the ejector, foot valve or submersible pump is installed below the pumping level.

Suction Head:
The head of the suction side of the pump. This is subtracted from the discharge head to determine the head being produced by the pump. It is a sum of the static, pressure and friction heads.

Suction Static Lift:
Same as Suction Static head. This term is only used when the pump centerline is above the suction tank fluid surface.

A chemical compound that can cause laxative effects and give off a medicinal taste in concentrations around 30gpg. In high concentration with high calcium hardness, it forms a white insoluble compound that is difficult to remove.

A yellowish solid element. The term also commonly described to water containing hydrogen sulfide gas. The presence of Sulfur is marked by a smell like rotten eggs.

A pit or pool for draining, collecting, or storing water. A chamber which provides water to the pump.

Supply Kit:
Usually a kit of all parts needed to connect a faucet or toilet to the pipes coming out of the wall. Usually includes stop valves, water connectors, and escutcheons.

Supply Stop:
The valve providing on/off toilet water supply control.

Surface Mount:
Typically refers to thermostats mounted on the outside of the tank that senses temperature through the steel tank.

Surface Pump:
A mechanism for removing water or waste water from a sump or wet well.

Suspended Solids:
Solid particles in water which are not in solution.

Service Victory. A designation for service weight cast iron drainage pipe.

Slang term for soldering. Also formation of condensation on the outside of pipes or toilet tanks.

A drain ell fitting with a long radius that allows for smooth passage of waste. Fittings with abrupt changes of direction, such as a vent tee, may only be used for vents.

Swing Joint:
A flexible sprinkler connection made by connection three threaded elbow fittings together.

Swing Spout:
Spout style that allows user to move or "swing" position of spout to where it's needed.