Glossary
Plumber Terms & Vocabulary
15 essential plumber terms with plain-English definitions: the vocabulary you’ll hear in training and on day one.
Key plumber vocabulary
These 15 terms come up constantly in plumber training, on the job and in interviews. Knowing them helps you follow instructions, document accurately and sound prepared.
- Backflow preventer
- A device that stops contaminated water from flowing back into the potable supply.
- Cleanout
- An access fitting used to clear blockages in drain lines.
- DWV
- Drain-waste-vent: the system that removes wastewater and vents sewer gases.
- Fixture unit
- A measure of a fixture’s load on the plumbing system, used to size pipes.
- IPC / UPC
- International Plumbing Code and Uniform Plumbing Code: the two main model codes in the U.S.
- P-trap
- A U-shaped pipe that holds water to block sewer gas from entering a building.
- PEX
- Cross-linked polyethylene tubing used for water supply lines.
- Potable water
- Water safe for drinking.
- Rough-in
- Installing pipes inside walls and floors before finishes go on.
- Slope (grade)
- The downward pitch of a drain pipe, commonly 1/4 inch per foot for smaller pipes.
- Sweat joint
- A copper joint made by soldering.
- T&P relief valve
- A temperature and pressure relief valve that prevents water heaters from exploding.
- Trim-out
- Installing fixtures and finishing work after walls are complete.
- Vent stack
- A vertical pipe that lets air into the drainage system so it flows properly.
- Water hammer
- A banging noise caused by a sudden stop in water flow.
Practice these terms
Test yourself with the free Plumber practice test: it includes vocabulary questions built from this list. For a complete course, see Plumber training.
Browse terms from every career in our career glossary.