Plumbing Glossary

Like most industries, the plumbing industry has its own language. The terms can make selecting or installing plumbing a challenge until you understand the terminology. We’ve compiled a list of the plumbing terms that you will find on Shop 4 Classics into our Plumbing Glossary. We hope you will find this information useful as you browse Shop 4 Classics.

- A -

acrylic -A glassy, thermoplastic material that is vacuum-formed to cast and mold shapes that form the surface of fiberglass bathtubs, whirlpools, shower bases, and shower stalls. Click here for acrylic bathtubs.

aerator -An apparatus that mixes air into flowing water. It is screwed onto the end of a faucet spout to help reduce splashing.

angle stop -A shutoff valve in which the inlet connects to the water supply pipe in the wall and the outlet angles 90 degrees upward toward the faucet or toilet.

Angle Stop

anti-scald -A valve that restricts water flow to help prevent burn injuries. See pressure balancing valve and thermostatic valve. In some areas, plumbing codes require anti-scald valves. Speak to a professional in your area for more information and help with code requirements. Click here for items featuring anti-scald valves.

anti-siphon -A device that prevents waste water from being drawn back into supply lines, possibly contaminating the water supply. See backflow preventer.

- B -

backflow -When water traveling from one system backs into any part of the main water supply system. Backflow is usually caused by siphoning.

backflow preventer -A device to prevent backflow. In some areas, plumbing codes require a backflow preventer for handheld showers, pullout faucet spouts, kitchen sprayers, etc. Speak to a professional in your area for more information and help with code requirements.

back siphonage -The backflow of contaminated or waste water from a plumbing fixture or vessel into a potable water supply due to negative pressure in the pipe.

backsplash -A raised integral portion of a wall mount sink or lavatory located at the rear to protect the wall.

basket strainer -Basket shaped strainer with holes allowing water to drain while catching food or other solids. Can also be closed to fill the sink with water.

Basket Strainer

bottom mount faucet -See widespread.

bonnet nut -A nut that covers a faucet valve stem concealing the valve and holding the stem or ceramic disk cartridge against the faucet's valve body.

bushing -A pipe fitting for joining pipes with different diameters. A bushing is threaded on the inside (see FIP) and outside (see MIP).

- C -

cast iron -Heavy metal formed by casting on molds. The metal is covered with a porcelain enamel coating to make fixtures such as the cast iron tubs found here at Shop 4 Classics. Click here for cast iron bathtubs.

centerset -A style of faucet that is installed on a lavatory with 4" center-to-center faucet holes and that has the spout and handle(s) combined into a single part. Click here for centerset faucets.

Centerset

ceramic disk valve -A type of valve that relies on two-part revolving disks in a sealed cylinder. Each disk has a port in it that, when aligned with the other, will allow water to pass through.

compression fitting -A pipe connection that seals without soldering. As a nut is tighten on one fitting, it compresses a washer or gasket around the second pipe, forming a watertight closure.

compression valve -A type of valve that works by raising or lowering a stem. Water passes through the valve by turning the faucet handle, which causes the stem to drop or rise.

console lavatory -A table-like lavatory in which the basin is attached to a wall at the back and by table or piano legs at the front. Click here for console lavatories.	Console Lavatory
coupling -Straight, sleeve-like fitting with female connections at both ends.

- D -

diverter -Valves which have a single inlet and direct water to one of two outlets. Diverters are used with handshowers, shower risers, tub & shower combinations, and kitchen faucet sprayers.	Handshower Diverter
DWV -(Drainage, Waste & Vent) The pipes in a plumbing system that remove waste water.

- E -

elbow -An angled fitting that alters the direction of the water line.

ell -See elbow.

escutcheon -A trim piece or decorative flange that fits beneath the faucet handle to conceal the faucet stem and the hole in the fixture or wall.

- F -

female IPS -Pipe connection where the threads are on the inside of the fitting. See FIP.

female threads -See FIP.

FIP -(Female Iron Pipe) Standard threads that are on the inside of a pipe fitting.

fitting -A general term that usually refers to faucets, shower valves, tub fillers, or various piping parts such as tees or elbows.

flow restrictor -A flow restrictor limits the amount of water that passes through it. For water conservation, plumbing codes require flow restrictors in some areas. Flow restrictors are commonly included with showerheads.

flex hose -A flexible pipe or tube usually made of braided stainless steel. Commonly used with widespread or Roman tub faucets to provide variable centers.

Flex Hose

flow rate -The rate by which water is discharged from an outlet. For example, the standard flow rate of a showerhead is 2.5 gallons per minute.

- G -

GPM -(Gallons Per Minute) The unit of measurement by which flow rate of faucets and showerheads are measured and regulated.

GPF -(Gallons Per Flush) The unit of measurement by which flow rate of toilets are measured and regulated. Current U.S. regulations for toilets require a maximum of 1.6 GPF.

- H -

hose bibb -An outdoor faucet with hose threads on the spout. Also commonly used to supply washing machines and wash basins.

- I -

ID -(International Association of Plumbing and Mechanical Officials) Certification body which tests and inspects listed products to verify compliance to the requirements of applicable codes and standards.

ID -(Inside Diameter) The diameter measurement taken from the inside of a pipe. A common method for sizing pipe.

inlet -An opening providing a means of entrance or intake.

IPS -(Iron Pipe Size) Pipe thread sizing system. Also measurement of the outside diameter of a pipe.

- L -

lavatory -Bathroom or washroom sink.

- M -

male IPS -Pipe connection where the threads are on the outside of the fitting. See MIP.

male threads -See MIP.

minispread -A smaller variation of a widespread faucet with separate spout and handles designed small enough to fit 4" center-to-center faucet holes.

MIP -(Male Iron Pipe) Standard threads that are on the outside of a pipe or fitting.

mixing valve -A valve that mixes hot and cold water in the valve to obtain a set temperature prior to delivery.

- N -

nipple -A short pipe installed between fittings. A pipe coupling that is threaded on both ends.

nominal size -Size used for identification only; not literal dimensions.

- O -

O-ring -Round rubber washer or gasket that is compressed to create a watertight seal, typically in a compression fitting.

OD -(Outside Diameter) A measurement of the diameter of a pipe as taken from the outside edge. A common method for sizing pipe.

offset -A tubular component which permits the offsetting of a drainage run in the same basic direction.

- P -

"P" trap -P-shaped section of drain pipe that prevents sewer odors from escaping into your home. Water is trapped in the pipe blocking gases from escaping through the drain.

"P" Trap

pedestal lavatory -A lavatory in which the bowl is supported by a single pedestal leg. Click here for pedestal lavatories.

pop-up drain -A drain mechanism that relies on a lever or rod to lift or pop up the drain stopper.	Pop-Up Drain
potable -Water that is safe to drink.

powder coat -A technique for applying paint to metal surfaces. The metal is covered with a powder of dry paint particles and is baked in an oven. This causes the powder to melt and harden into a tough, colorful finish.

pressure balancing valve -A mixing valve that maintains a constant water temperature by balancing incoming hot and cold water supplies. Fluctuations in either hot or cold water pressure may cause overall outlet pressure to drop but the temperature is regulated to remain consistent. Click here for items featuring pressure balance valves.

PVD -(Physical Vapor Deposition) A very durable titanium or zirconium coating that resists tarnish, scratches, and corrosion. It is used mostly to protect faucets with a brass finish.

- R -

reducer -See bushing.

riser -An upright or vertical pipe that feeds water to a fixture such as a showerhead.

rough-in -The unfinished ends of drain or supply lines marking where fixtures and drains will eventually be installed.

- S -

seat -The fixed part of a valve. The stem assembly will move up and down against the seat to open and close the valve.

self rimming -A style of bathroom lavatory or kitchen sink with a finished lip or rim that installs on top of a counter without requiring a metal sink rim.

shutoff valve -The valve that allows water supply to be cut off to one fixture without affecting the water supply to the entire house or building. Common for use with clawfoot tubs, sinks, and toilets.

slip joint -A connection made with compression fittings.

spud -A short section of pipe or a threaded fitting that completes a connection.

stem assembly-The moving part of a valve that controls the amount and temperture of water released by moving up and down against the seat to open and close the valve.

stem -A small shaft or rod that projects through the faucet valve and to which the handle is installed.

stop -See shutoff valve.	Straight Stop
straight stop -A shutoff valve that is installed on a supply line between the floor and the faucet or toilet. Unlike an angle stop, a straight stop does not change the direction of water flow.
stub -See rough-in.

- T -

tailpiece -The tubular part of a lavatory drain that runs from the drain flange to the trap.

tee -A T-shaped fitting with three openings.

thermostatic valve -A mixing valve that automatically maintains the temperature setting by regulating fluctuations in water temperature at the water inlets and immediately adjusting the ratio of hot and cold water that is discharged by the valve. Click here for items featuring thermostatic valves.

top mount faucet -See centerset.

trim kit -Refers to the outside decorative parts that conceal a faucet rough-in.

- U -

undercounter -A style of lavatory which is positioned under the cutout of the countertop.

union nut -A fitting that joins two sections of pipe.

- V -

vacuum breaker -A anti-siphon device that prevents waste water from being drawn back into supply lines, potentially contaminating the water supply. A type of backflow preventer.

valve -A device that regulates water flow.

vitreous china -A non-porous ceramic that is coated with a ceramic glaze to form toilets and lavatories.

- W -	Waste & Overflow
waste & overflow -A bathtub drain assembly that has an outlet at the top to remove overflow water when filling the tub and an outlet at the bottom to remove waste water when the tub is drained.
water closet -Toilet.

widespread -A style of lavatory faucet where the spout and handles are separate. Flex hoses are used between the spout and handles to allow adjustable centers, although this style of faucet is typically used on 8" or 12" centers. Click here for widespread faucets.

Widespread Faucet