Blog > Bathroom Plumbing - Jargon Explained

Bathroom Plumbing- Jargon Explained

Planning Advice

By Tamsin Allen

This may seem like a boring post, but it is a really necessary one. It is easy to be left clueless when your plumber starts running through what you need for your bathroom refurbishment, but save this list somewhere safe and you’ll soon be planning your plumbing system with him.

bathroom plumbing jargon explained 01

Acrylic - A thermoplastic used on the surface of bathtubs and whirlpools. Generally comes in sheets and is formed to the shape of the mold (tubs/showers) in the factory. Generally fiberglass is added to the back for strength.

Adaptor - A fitting that joins two different types of pipes together. Or a fitting that joins threaded with none threaded pipe (as in: female adaptor or male adaptor).

Aerator - A part at the end of a tap spout, which mixes air into the dropping water, thereby aerating the water.

Air admittance valve - A valve designed to vent a stack pipe within a building by drawing air into the pipework when an appliance is discharged. The valve automatically reseals the pipework when the air pressure equalises so that foul air is contained within the pipework.

Air Gap - Air-filled space allowing contaminated water to discharge freely, preventing the contaminated water from ever siphoning back into the potable water supply.

Airlock - Trapped air in pipework where, due to its layout, the air cannot escape naturally resulting in no or very little flow of liquid along the pipe.

Anti-Vacuum - A one-way valve, which allows air into a drainage system, found by a basin or at the top of an internal soil pipe to balance pressures and prevent the water in U-bends being sucked out.

Automatic air vent - A mechanical device, which automatically releases air trapped within a water system - normally fitted at the highest point of a plumbing system.

Angle Stop - An "emergency" stop (valve) that is usually installed before the water supply line (below) to toilets and taps. Angle stops are to be shut off in case of an emergency or repair and are generally not designed for daily on and off usage. The difference between a "straight stop" and an "angle stops" is that the "angle" stop changes direction by 90 degrees while a straight stop is like most valves and does not change direction.

Back siphonage - The reverse flow of liquid caused by siphonage from a cistern or appliance into the pipe feeding it, can lead to a contamination of the water supply.

Back-to-wall cistern - A cistern separate from the WC pan, which may be concealed behind a wall or within fitted furniture.

Ball cock - A valve used to control the flow of water into a tank or cistern, the valve being controlled by a float on the surface of the water in the tank/cistern. AKA Float Operated Valve.

Bar - The unit of measurement of water pressure - one bar is approximately equivalent to a column of water 10m high or 14.5 lbf/in² or 100 kPa (kilopascal).

Basin - A bowl for washing, typically attached to a wall and having taps connected to a water supply; a washbasin.

Bidet - Pronounced B-day, is a plumbing fixture similar to a toilet bowl (but no solids are to be deposited in a bidet) used for washing genitals and posterior areas of the body. It is floor mounted, usually next to a toilet, and incorporates a washing basin and tap. Bidets are very popular in some countries such as France and the UK. A bidet is commonly equipped with a hot and cold mixing valve to provide warm water for washing.

Bleed valve - An air release valve used to release air from a central heating system - found on all water radiators and sometimes at high points in the pipework.

Bottle trap - A form of trap for basins and sinks etc - usually in a cylindrical form where the bottom can be unscrewed from the body for cleaning etc.

BSP - Abbreviation for British Standard Pipework

Capillary connector - A pipe coupling with a tight fit on the pipe, the gap being filled with solder once heated to provide a watertight seal. Some couplings incorporate a solder ring (AKA a Yorkshire fitting) while others need solder applied once the joint has been heated. The joints are not reusable. Available as straight, 'T', elbow and in other configurations.

Ceramic taps - Taps which use a rotating ceramic disc to control the flow of water; requiring only a quarter handle rotation to turn the flow on or off.

Check valve - A plumbing fitting designed to allow water flow in one direction only.

Cistern - A fixed container for holding water at atmospheric pressure, normally applied to the local water storage to flush a WC. It is normally fitted with a float operated valve and overflow pipe.

Clamping the nipple - A nipple is a short piece of pipe, usually with male threading at both ends, and is used for attaching two different couplings or fittings. Using a nipple wrench, you can clamp the nipple from the inside so that when you unscrew it from the attached fittings you won’t damage the threads.

Close coupled WC - A pan/cistern combination where the underside of the cistern rests directly on the back of the WC pan creating a compact unit with low overall height. Generally the cistern is operated by a lever mounted on the front of the cistern or (more modern) a push button on the cistern top cover.

Cockhole cover - A round plate, used to cover unused tap holes in your sink. In the old days taps were called cocks and some of this terminology remains. This is also called a tap hole cover

Cold water storage tank - A fixed container for holding water at atmospheric pressure usually used for providing a feed to domestic cold water and/or to a vented domestic hotwater system.

Combination boiler - AKA "combi" - a unit which combines both a central heating water heat exchanger and a domestic water heater in one compact, self-contained unit. Unlike an vented heating and hot water system, a combi does not store hot water, rather it heats water as and when required either directly from the cold mains (for the domestic hot water) or within a pressurised 'sealed' central heating loop.

Compression connector - A pipe coupling using threaded nuts to compress an 'olive' on the pipe to provide a watertight seal. More expensive than capillary joints but are easy to fit and generally reusable. Available as straight, 'T', elbow and other configurations.

Copper - The material used for hot and cold water pipes, generally 15mm to basins and mains fed taps and 22mm to baths.

Coupling - A fitting that joins two pieces of pipe (or other fittings) together.

CWP - Abbreviation for cold working pressure.

CWT - Abbreviation for Copper Water Tube (refers to nominal pipe size).

Deck mounted taps - Taps designed to mount on the edge of the basin or bath (rather than being wall mounted).

Diverter - Valves which direct water to various outlets. They are used in showers, tub & shower combinations, bidets, Roman tub fillers and kitchen tap sprayers.

Down pipe - The soil pipe that rises vertically through a house from the drainage connecting toilets, baths and basins.

Durgo valve - A valve designed to vent a stack pipe within a building by drawing air into the pipework when an appliance is discharged. The valve automatically reseals the pipework when the air pressure equalises so that foul air is contained within the pipework. Also knows as an Air Admittance Valve.

Dual flush cistern - A WC cistern offering the option of a water saving or full volume flush, normally determined by how the handle is operated. DWV - Abbreviation for Drainage, Waste & Vent systems.

Dynamic pressure - The pressure when the water IS flowing

Earth bonding - A legal safety requirement to have all metal parts within a plumbing system connect to earth to prevent them becoming electrically dangerous.

Earth bonding strap - A metal strap used to achieve 'earth bonding' by joining the metal pipes and fittings together to provide an electrical earth path. Elbow aka ELL - A fitting with two openings that change directions 90 degrees

Electrical heating element - A component used in an instantaneous electric shower to heat the water as it flows through.

Elongated - The shape of the front of a toilet bowl. Generally 2" longer than the standard "round front" bowl

Elongating the pipe - A short length of pipe installed between couplings or other fittings

Enamel - An opaque vitreous composition applied by fusion to the surface of metal fixtures such as cast iron and pressed steel tubs, lavatories and sinks. Do not confuse enameled steel with enameled cast iron. Cast iron with enameling is much more durable

Escutcheon - A flange or shield beneath a wall mount tap handle. This part covers the tap stem and the hole in the fixture or wall

Essex flange - A fitting inserted into the side of hot water cylinders, just below the top seam, which purges the hot water of air before it is drawn off into the outlet. Normally used in the feed for shower pumps. Alternatives York and Surrey flanges are fitted into the top outlet of hot water cylinders.

Expansion tank - A tank which will accommodate the expansion of water within a system as it heats up or to absorb pressure shock waves to reduce water hammer. May be open or sealed depending on whether the system is vented or sealed. FHT - Abbreviation for female hose threads

Fiberglass - Glass in a fibrous form used in making products such as boats and bathtubs

Finishes - The following finish abbreviations are generally used by many (not all) tap manufacturers: • BC = Brushed Chrome • BN = Brushed Nickel • CP = Polished Chrome • PB = Polished Brass • SN = Satin Nickel • BL = Black • WH = White

FIP - Abbreviation for female pipe threads

Fixture - Broad term in plumbing/kitchen/bath that could be an entire toilet, sink, tub, etc OR it could be the devices that provide a supply of water

Float operated valve - see Ball cock.

Gate valve - A hand operated on/off valve permitting water flow in either direction.

Grey water - The waste water from baths, basins, sinks, washing machines, dish-washers etc., which has been used to clean things and which is considered to be only mildly dirty.

Handshower - A showerhead designed with a handle that is connected to a water supply via a flexible hose

Hardness leakage - Calcium and magnesium are the two minerals which make cause water hardness, and which produce a hard scale in piping, water heaters, steam irons, and pots and pans. When hard water is passed through a bed of ion exchanger, the positively charged calcium and magnesium ions are replaced with sodium, and the water becomes softer. Leftover traces of hardness in the mineral bed is known as hardness leakage.

Header tank - See Cold water storage tank.

Heat exchange - The unit which transfers the heat from the burner to the water. In Combi boilers and Multipoint heaters these generally have a low water volume.

High level cistern - A cistern mounted high on the wall and connected to the WC pan by a long flush-pipe, the flush is powerful and operated by a pull-chain and handle.

Hot water cylinder - A closed vessel (normally cylindrical) used to store heated water under pressure greater than atmospheric.

ID - Abbreviation for "inside diameter. In plumbing most pipes are sized by "nominal" (approx.) I.D. which means that when plumbers say 3/4" pipe for example it generally means that the outside diameter is wider than 3/4"

Immersion heater - An electrical water heater inserted into a hot water cylinder - it incorporates both the heating element and the thermostat). Two may be used with a single cylinder - one on 'off peak' electricity, the other switchable for use at other times if necessary.

Indirect hot water cylinder - A hot water cylinder where the water heated by the boiler is fed through a coil of piping inside the cylinder to heat the domestic water. The tank often incorporates an electric immersion heater so that the tank can be heated when the boiler is switched off for the summer.

Instantaneous electric shower - A shower that electrically heats the water as the water flows through it.

Instantaneous gas water heater - An appliance which heats water on demand as water flows through it.

IPS - Generally an abbreviation for "iron pipe size." Sometimes it means male pipe threads

Lockshield valve - Fitted at the return side of each radiator and used to balance the system when it is first installed. Generally there is no need to adjust them once set (they are normally covered with a cap), if they are closed to allow for the removal of a radiator, count the turns to the off position so that they can be reset when required.

Low level cistern - A cistern mounted on the wall just above the WC pan with a short flush pipe. Generally the cistern is operated by a lever mounted on the front of the cistern or (more modern) a push button on the cistern top cover.

Male into female - Also referred to as “mating”. In the world of plumbing, whether it’s a pipe, a hose or a fitting, anything with threading on the outside is considered male. Female thread is on the inside.

MHT - Abbreviation for male hose threads

Mini Widespread - A special style of bathroom basin tap having separate spout and handles. But designed small enough that it will fit 4" center-to-center tap holes

MIP - Abbreviation for male pipe threads

Mixer shower - A simple shower using a valve to combine the domestic hot and cold water supplies to provide the required temperature and flow.

Mixer taps - A tap with separate hot and cold inputs and having a single output. The inputs can be adjusted to give the required temperature and flow.

Monobloc taps - A mixer tap for a single mounting hole. The input pipes are smaller than 'normal' taps.

Multi Point water heater - An instantaneous water heater, which will supply water to more than one outlet.

OD - Abbreviation for "outside diameter." The measurement of the diameter of the pipe as taken from the outside edge

OEM - Abbreviation for Original Equipment Manufacturer

O-ring - A circular, rubber, sealing ring - often found in mixer taps and in waste pipe fittings.

Olive - A brass or copper compression ring used in compression couplings.

Ovality - The difference between the most wide OD and the most narrow OD on a pipe or tube. Found by subtracting the minimum outside diameter from the maximum outside diameter on a pipe Overflow pipe - A pipe connected from a tank or cistern to discharge any surplus water into an area without causing damage, normally it will only come into use when there is a fault (i.e. a leaking valve etc). See also Warning vent.

P-bend - A form of trap used under basins, baths etc.

PEX - Abbreviation for Polyethylene Plastic Material (stronger than, P.E.)

Pipes - Unlike tubes, the measurement of a pipe (i.e. 2") roughly references the inside diameter (ID) of the pipe and not the outside diameter (OD). A 2" Sch 40 pipe actually has an OD of 2.375", a wall thickness of .154" and an ID of 2.067"

Pop up assembly - The drain mechanism of a tap. The drain stopper "pops" up and down

Porcelain - A white ceramic ware that consists of quartz, kaolin, and feldspar. It is fired at high temperature on steel or cast iron to make the surface of some bathtubs, kitchen sinks and bathroom lavatories. Many times the word "porcelain" also refers to porcelain china which is a ceramic product with porcelain glaze

Porcelain Enamel - Vitreous enamel. Many times the words "porcelain enamel" refers to pressed steel (not recommended by us) products with a porcelain glaze. When purchasing "fixtures" we like to recommend either a porcelain glaze on top of ceramic, or porcelain glaze on top of cast iron

Power shower - A shower using a pump to boost the flow of water to give a powerful shower spray. Generally used where there is insufficient water pressure on gravity fed water supplies.

PR - Abbreviation for "Pressure Regulator." Generally means water pressure regulator. Most codes require one if water pressures ever exceeds 80 pounds at any time on domestic potable water systems inside a structure

Pressure balance valve - A shower mixing valve that automatically maintains balance between hot and cold water supplies by immediately regulating fluctuations in pressure. As a result the outlet temperature remains constant

Pressure relief device - A safety device fitted to relieve excessive pressure within an electric shower heater - generally a 'use once' device which requires replacement after the problem has been rectified.

Pressure system - A water heating system for hot water to baths and basins which is sealed. Instead of the vent found in a header tank, a pressure vessel controls pressure. The advantage is that the pressure is high and so good for showers. Current Building Regulations require that if fitting this system, the details are submitted as a formal application for approval.

Pushfit connectors - Plumbing connector which just push onto the pipework rather than compression or capillary connectors - maybe plastic but suitable for both hot and cold water - sometimes referred to as 'Speedfit connectors' (one of the early brands). Available as straight, 'T', elbow and other configurations. PTFE tape - Polytetrafluorethylene tape used to seal threaded plumbing joints.

PVD - Physical Vapor Deposition (used mostly with polished brass or gold finishes). This is a modern plating process used in faucet manufacturing. Vaporized zirconium reacts with nitrogen and other gases to form a VERY durable plated surface. Unlike former days when polished brass would easily tarnish over time, polished brass finishes with PVD are extremely durable and won't generally tarnish or discolor

Quarter Turn Tap - You only need to turn the lever 1/4 of a full circle to go from off to full on. This is possible thanks to ceramic disc cartridge valves. The old technology that used rubber washers required you to turn the handles around a few times to turn on and off.

Reducer - A fitting that connects pipes of different sizes together Riser - A vertical assembly of pipe and fittings that generally distributes water upward

Rising main (AKA a riser) - The water pipe that supplies pressurised mains water to taps, tanks, appliances etc. Normally there is a single stop cock which controls the rising main within a property.

Round front - The standard shape of the front of a toilet bowl. Generally about 2" shorter than the optional "elongated" bowl S-bend - A form of trap used under basins, baths etc.

Schedule (SCH) - The "Schedule" designation tells you how thick the wall is for any size of pipe with the higher schedule numbers meaning a thicker wall. The most common schedules are Sch 40 and Sch 80, but the actual wall thickness varies depending on the size of the pipe

SDR - Standard Dimension Ratio (SDR) used for determining the minimum wall thickness for pipe. SDR is found by dividing the outside diameter (OD) of the pipe by the wall thickness measurement. To find the minimum wall thickness of a pipe you simply divide the OD by the SDR

Servicing Valve - A valve for shutting off the flow of water in a pipe connected to a water fitting to facilitate the maintenance or servicing of that fitting.

Single lever mixer tap - A mixer tap with a single lever handle to controls the water flow of both the hot and cold water supplies.

Solder connector - see capillary connector.

Stack pipe - High level vent pipe for the main soil pipe.

Static Pressure - The pressure when NO water is flowing

Stop cock - A hand operated on/off valve permitting water flow in one direction.

Straight Stop - An "emergency" stop (valve) that is usually installed before the water supply line (below) to toilets and taps. Stops are to be shut off in case of an emergency or repair and are generally not designed for daily on and off usage. The difference between a "straight stop" and an "angle stops" is that the "angle" stop changes direction by 90 degrees while a straight stop is like most valves and does not change direction

Street Elbow - An elbow (90 degree bend) fitting that has a male end (same size as pipe) on one side and a female end (pipe fits inside this size) on the other side

Surrey flange - A fitting inserted into the top of hot water cylinders which purges the hot water of air before it is drawn off into the outlet. Normally used in the feed for shower pumps. Surrey Flange will suit female cylinder outlets - for male cylinder outlets, the equivalent is a York flange.

Sweating the pipe - soldering two pipe fittings together so that water cannot leak out.

Tail (on a tap) - The threaded section (or copper pipes on a monobloc tap) that are connected to the water supply pipe.

Tap seat - The supply orifice within a tap body (except ceramic taps) on to which the washer is compressed to seal off the water.

Thermostatic mixing valve - A hot and cold water mixing device which automatically adjusts for variations in the temperature and/or pressure of the incoming supplies, to maintain a selected temperature at the outlet.

Thermostatic radiator valve (TRV) - A Radiator control valves which automatically opens and closes as necessary to achieve the pre-set room air temperature.

Thermostatic valve - A pressure balancing (normally shower) mixing valve with automatic temperature control. When temperature or pressure fluctuations occur at the water inlets, a thermal actuator adjusts the hot and cold ratio to maintain the original temperature setting.

Trap - A water filled seal in the waste run from a bath, basin, or sink, etc which prevents fumes coming back from the drains. A curved section of drain line that prevents sewer odors from escaping into the atmosphere. All "fixtures" that have drains must have a "P" trap installed. A toilet is the only plumbing fixture that has an "S" trap instead of a "P" trap.

Tubes - Unlike pipes, the measurement of a tube (i.e. 2") corresponds to it's outside diameter (OD). So the outside diameter of a 2" tube is truly 2".

Two hole mixer tap - A mixer tap requiring two separate holes for the water feeds in the sink etc. - as opposed to a Monobloc tap.

U-bend - A form of trap - often used to refer to a WC trap which maintains a residual amount of the waste water to prevent smells from the drains coming back into the house.

Valve - Any of various devices that regulate the flow of gases, liquids, or loose materials through piping or through apertures by opening, closing, or obstructing ports or passageways.

Vanity - A bathroom storage cabinet beneath the counter. Some plumbers also call a bathroom basin a vanity.

Vent pipe - An uninterrupted safety pipe, which allows air or the expansion of water within a hot water system to escape - normally positioned over a tank/cistern so that any water is discharged into it.

Vitreous - A surface material on some plumbing fixtures derived from or consisting of glass. It is low in porosity and is translucent.

Wall hung toilet - A WC where the pan is suspended or hung from a wall rather than being fitted to the floor.

Warning vent - An overflow pipe positioned so that its outlet is in a conspicuous position where any discharge can be readily seen.

Waste and overflow - The drain assembly for a bath, basin and sink. The outlet at the top removes the "overflow" water during tub filling and the drain at the bottom removes "waste" water when the tub is drained. Not all of these have an overflow facitity but they must all have a waste.

Water closet – Toilet

Widespread - A style of bathroom basin tap having separate spout and handles. Usually 8" from center of handle-to-handle. Some widespread taps can be set with handles up to 12" apart.

Wiggling the snake - Also known as a “toilet jack,” a “closet auger” or an “electric eel,” the plumbing snake is a flexible auger used to unclog toilets that are beyond the help of a plunger. It takes practice to learn how to wiggle it correctly.

York flange - A fitting inserted into the top of hot water cylinders which purges the hot water of air before it is drawn off into the outlet. Normally used in the feed for shower pumps. A York Flange will suit male cylinder outlets - for female cylinder outlets, the equivalent is a Surrey flange.

Yorkshire fitting - A capillary connector incorporating a solder ring - an original brand name.

Bathroom Plumbing- Jargon Explained

Tamsin Allen

Tamsin has a background in design, art direction and advertising and a love for interiors, helping build the Foam & Bubbles brand and managing all their social media channels is a job that never gets tiring for Tamsin. Creating a brand that strives to provide a unique experience with a light-hearted attitude continues to be fun to work on every day.


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