Plumbers Terms

Glossary of Terms & Definitions

This Plumbers reference guide is for the Do It Yourself plumber.  I have more articles on DIY plumbers on the site and at AO Smith Repair.

ABS (Acrylonitrile butadiene styrene)
Rigid black plastic pipe used only for drain lines.

Access Panel
An opening in the wall or ceiling near the fixture that allows access for servicing the plumbing/electrical system.

Adaptor
A fitting that unites different types of pipe together, e.g. ABS to cast ironpipe.

Cleanout
A plug in a trap or drain pipe that provides access for the purpose of clearing an obstruction.

Closet Auger
A flexible rod with a curved end used to access the toilet’s built-in trap and remove clogs.

Closet Bend
A curved fitting that connects the closet flange to the toilet drain.

Closet Flange
An anchoring ring secured to the floor. The base of the toilet is secured to this ring with bolts.

Coupling
A fitting that joins two pieces of pipe.

CPVC (Chlorinated Polyvinyl Chloride)
Rigid plastic pipe used in water supply systems, where code permits.

DWV
Abbreviation for drain, waste and vent.

Elbow
A pipe fitting with two openings that changes the direction of the line. Also called an ell. It comes in a variety of angles, from 22 1/2° to 90°.

Fall/Flow
The proper slope or pitch of a pipe for adequate drainage.

Fixture
In plumbing, the devices that provide a supply of water and/or its disposal, e.g. sinks, tubs, toilets.

Flux
The paste that is used in soldering metal joints. Flux aids the process by preventing oxidation of the joint.

I.D.
Abbreviation for inside diameter. All pipes are sized according to their inside diameter.

O.D.
Abbreviation for outside diameter.

PB (Polybutylene)
Flexible plastic tubing used in water supply systems where allowed by code.

Plumber’s Putty
A pliable, popular putty used to seal joints between drain pieces and fixture surfaces.

PVC (Polyvinyl Chloride)
A rigid white or cream colored plastic pipe used in non pressure systems, such as waste and vent systems.

Reducer
A fitting that connects pipes of different sizes.

Riser
A vertical assembly of fittings and pipes that distributes water upward.

Rough-In
The portion of a plumbing installation that includes running the water supply lines and drain, waste & vent lines to the proposed location of each fixture.

Run
A complete or secondary section(s) of pipe that extend from supply to fixture or drain to stack.

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.

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

Solder
A metal alloy that is melted to join or mend metal surfaces; also, the act of melting solder into the joint.

Stop Valve
A valve that controls the flow of water to an individual fixture, allowing water supply to be stopped to one fixture without affecting the water supply to other fixtures.

Tee
A T-shaped fitting with three openings used to create branch lines.

Trap
Curved section of a fixture drain line, designed to hold water thus preventing sewer gases from entering the house.

Union
Three-piece fitting that joins two sections of pipe, but allows them to be disconnected without cutting the pipe. Used primarily with steel pipes, but never in a DWV system.

Vent Stack
The upper portion of the soil stack above the topmost fixture through which gases and odors escape.

WYE
A Y-shaped fitting with three openings used to create branch lines.

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Plumbers Terms