Following are a few common terms in plumbing in case you are unfamiliar with them:

Air-lock
Air trapped in pipes, causing a reduction or complete stop in the flow of liquid.

Adaptor
Device that fits different types of pipes together.

Back-siphon
A condition where the flow of liquid is reversed and siphons back towards the source, which can cause contamination of the source.

Bar
The unit that water pressure is measured in.

Bleed valve
A valve that releases air from the central heating system.

Cistern
A water tank that maintains a back-up supply of water for the toilet, and prevents back-siphonage into the mains.

Combination boiler / Combi boiler
A device which combines a domestic water heater and a central heating water heat exchanger, and heats water on demand.

Coupling
A device that connects two pieces of pipe.

Fixture
A broad term for apparatus that serve in the supply or disposal of water, e.g. sinks, tubs, basins or toilets.

Flange
Those often referred to in plumbing include the Surrey flange and the York flange which fit onto the top of a hot water cylinder and allow the hot water to be drawn away from the tank, without any air. The Essex flange serves the same purpose but is fitted into the side of the hot water cylinder.

Grey water
Waste water from domestic processes.

Hot water cylinder
Insulated hot water tank, usually stores water under pressure.

Immersion heater
An insulated electric resistance heater that sits inside a hot water cylinder and heats the water.

Power shower
A shower incorporating a device that increases water pressure, thus using more water but creating a more powerful spray.

PVC
PolyVinyl Chloride plastic used for water supply pipes.

Trap
Section of the drain which holds water, creating a seal that stops fumes from waste travelling back into the house. The U-bend on the toilet is an example.

Vent pipe
Pipe that allows the release of air or water from hot water system