Plumbing Terms - Glossary of Plumbers Terminology

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Trap Bend

A trap bend is a plumbing trap that is the shape of the letter S, J, U or P . Some shapes are disallowed in many parts of the country as they can create a siphoning situation, pulling water out of the trap.

Trap Primer

With a trap primer is meant a small feeder line that connects the water line directly to a drainage trap that releases a small amount of water into the trap in the event that it should run dry, maintaining a water seal inside the trap.

Trap Seal

With the trap seal is meant the height of the water inside a toilet bowl when it's "at rest". The water automaticaly provides the water seal which prevents sewer gases from entering your home. It is measured from the top of the dam down to the inlet of the trapway. The trap seal is also referred to as deep seal.


With an undercover is meant the underside portion of some faucets which also use a top shroud to cover an assembled faucet waterway.

Undermount Lavatory

An Undermount Lavatory is a type of lavatory of which the body of the sink attaches to the underside of the countertop. Depending on the design of the sink, faucets can be mounted on the countertop or the sink itself.

Union Plumbers

Union Plumbers are part of an organization of workers who have banded together to achieve common goals like better working conditions. This may include the negotiation of wages, work rules, complaint procedures, rules governing hiring, firing and promotion of workers, benefits, workplace safety and policies.


A urinal is a kind of toilet which receives only liquid body waste and conveys the waste through a trap seal into a gravity drainage system.


In the plumbing trade a Valve is a device that regulates the flow of liquids and gasses. Also the rough-in part of a faucet that is concealed in the wall or undercounter.

Valve Body

In plumbing the term Valve Body refers to the housing for a valve cartridge. The valve body contains an inlet and an outlet, with the valve cartridge controlling the flow of water.


The venting system, or plumbing vents, consists of pipes leading from waste pipes to the outdoors, usually through the roof. Vents provide a means to release sewer gases outside instead of the house. Vents also admit oxygen to the waste system to allow aerobic sewage digestion.

Vent piping

The vent piping provides ventilation to the drainage system and prevents trap siphonage and back pressure from clogging or contaminating the drainage system. A local vent pipe is a duct or pipe connected to the house side of a fixture or trap through which toxic and nasty vapors may be removed from a room.

Vessel Sink

A Vessel Sink is a lavatory, reminiscent of china washbasins with finished inside and outside walls, that is designed to sit on the countertop.

Wall Bracket

A Wall Bracket is an adjustable bracket which attaches to a slide bar or hanger allowing the user to pivot and rotate the position of a handshower.