Plumbing Terms - Glossary of Plumbers Terminology

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First Draw

With first draw is meant the water that has been sitting in pipes or plumbing fixtures overnight and is first drawn when taps are opened in the morning. For instance, where lead is present in plumbing, this water would have the highest levels of lead contamination.

Fixture Branch

A fixture branch is a pipe that carries wastes from non-toilet plumbing fixtures directly to the building drainage system. It is also called a waste pipe, wet vent, or a fixture drain.

Fixture vent

In the plumbing trade fixture vents are used to ventilate plumbing fixtures, to prevent siphonage, to relieve pressure on trap seals, and to draw off back pressure from gases generated by decomposing sewage. It is usually run as a continuous vent, that is, only one fitting is used to connect vent pipe, waste pipe, and fixture trap or branch.


In the plumgbing and piping industry a flange is a plate or ring to form a rim at the end of a pipe when fastened to the pipe (for example, a closet flange). A blind flange is a plate for covering or closing the end of a pipe. A flange joint is a connection of pipes, where the connecting pieces have flanges by which the parts are bolted together.

Flapper Flush Ball

A Flapper Flush Ball is the moving part of the flush valve that seals the water into the tank or allows water to exit the tank for the flush cycle. The most common replacement part used on conventional toilets.

Flex Coupling

A Flex Coupling is the rubber coupling used to join DWV Pipe. Can be used to connect PVC to Clay or Cast Iron above or below ground. Also used for repairs, and attach by used of steel band clamps.

Flow Control Valve

A flow control valve is a device designed to reduce water flow to a plumbing fixture. Often used to improve efficiency and reduce operating costs. Also a check valve that prevents flow reversal when heater is turned off.

Garbage Disposal

A garbage disposal is an electrically motorized kitchen appliance inside a kitchen drain that grinds waste food and mixes it with water before disposing of it through standard plumbing drainage pipes.


A gasket is a flat device that is usually made out of fiber or rubber. In the plumbing industry gaskets are used to provide a watertight seal between various metal parts or joints.


Gelcoat is a colored, polyester-resin material applied to the surface of a molded part. The gelcoat hardens to a smooth, durable form and becoming an integral part of the laminate. Fiberglass pools and spas usualy have gelcoat finishes.

GPF - Gallons Per Flush

GPF stands for Gallon per flush, generally the toilet's gallons per flush are printed on the porcelain behind the toilet seat. New toilets, per federal law, are only allowed to deliver 1.6gpf or less. In many years past, toilets flushed as much as 7-8gpf. 

At first, manufacturers tweaked the valves and floats in the tank to reduce the water used without making any changes to the tank or bowl. The two most common adaptations were to install a flush-valve flapper which closes before all the water escapes the tank (early-close flapper) or to install a plastic bucket, or toilet dam, which retains some water in the toilet tank behind the dam, thus lowering the volume of flush.

Gravity-Flush System

A Gravity-Flush System uses the natural weight of the water in the tank to generate enough pressure to flush a toilet. The water pressure forces the water from the tank down into the toiletbowl, then through the S-shaped trapway. A siphoning action completes the flush. This flushing system is quieter than the pressure-assisted system, simple, and requires less maintenance than other, more complex flushing systems, but can clog up.

Gray Water

With gray water is meant the household water recycled from sinks, bathtubs, washing machine and showers. The grey water is then among other things used to water the landscaping.

Grease Trap

Grease traps (also known as grease interceptors, and grease recovery devices) are plumbing devices designed to intercept most greases and solids before they enter a wastewater disposal system.

Heating Plumbers

A heating plumber focuses on the installation repair and maintenance of heating equipment like boilers and heaters. Heaters are commonly used to generate heating (i.e. warmth). Heaters exists for all states of matter, including solids, liquids and gases.

House drain

With a house drain is meant the lowest piping in a house drainage system, this pipe receives the discharge from soil, waste, and other drainage pipes, and then carries such discharge to the house sewer. The house drain ends just outside the front or foundation wall of the building, and operates by gravity.

House sewer

the house sewer is the section of sewer pipe which runs between the house drainage system and the connection to the public sewer or septic tank. House sewers should convey the waste of only one residence.

HVAC - Heating, Ventilating, and Air Conditioning

HVAC is an initialism that stands for the closely related functions of Heating, Ventilating, and Air Conditioning — the technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer. Refrigeration is sometimes added to the field's abbreviation as HVAC&R or HVACR, or ventilating is dropped as in HACR (such as the designation of HACR-rated circuit breakers).

Hydraulic fittings

Hydraulics use extremely high fluid pressures to create useful work, such as in the actuators for machinery such as backhoes. As such the hydraulic fittings are designed and rated for much greater pressures than those experienced in general piping systems and they are generally not compatible for use in general plumbing. More information on hydraulics and their fittings can be found in the hydraulic machinery article.