Stopcock / stop tap
The main valve that controls water entering a property.
You may see it near where the supply enters, sometimes below a sink, in a cupboard or near a meter.Explore Leak repairPlain-English plumbing terms
Plumbing terms, explained simply.
Use these short definitions when a fitting, pipe or toilet part is mentioned in an enquiry. They are for clearer descriptions, not DIY repair instructions.
Choose the closest term, then use the linked route if it matches what you can see. A photo can also help explain the fitting or symptom.
Water controls and pipework
Isolation valve
A small valve that can turn off water to one fitting or appliance.
It may be on pipework serving a toilet, tap or washing-machine connection.Explore Tap repairFlexi hose
A flexible connector between pipework and a fitting or appliance.
It is often found below taps, toilets and washing-machine connections.Explore Leak repairCompression fitting
A pipe connector tightened around a pipe with a nut and ring.
It can appear on visible copper or plastic pipework, often near valves or earlier repairs.Explore Leak repairToilet and bathroom terms
Cistern
The tank that stores water for a toilet flush.
It may sit behind, above or inside the toilet.Explore Toilet repairBall valve / fill valve
A cistern part that controls water refilling after a flush.
It is found inside the toilet cistern and can be relevant when water keeps running or refilling sounds unusual.Explore Toilet keeps runningOverflow
A route for excess water when a cistern or tank keeps filling beyond its normal level.
It may be visible at a toilet cistern, tank or an external overflow pipe.Explore Toilet keeps runningMixer tap
A tap that mixes hot and cold water through one spout or control.
It is common at kitchen and bathroom basins, and on some baths.Explore Tap repairWaste and drainage terms
Trap
A curved section of waste pipe that holds water to help prevent smells returning into a room.
You may see one beneath a basin, sink, bath or shower waste.Explore Bathroom plumbingWaste pipe
Pipework that carries used water away from a basin, bath, shower or appliance.
It can be visible below sinks, baths, showers and appliance connections.Explore Bathroom plumbingSoil pipe
The larger pipe that carries toilet waste away from a property.
It may run behind a toilet or along an external wall.Explore Blocked toiletRadiator terms
Radiator valve
A valve that controls water flow into or out of a radiator.
It is usually found at the lower side of a radiator.Explore ServicesTRV
A thermostatic radiator valve: a radiator control with a temperature setting.
It is fitted on one side of many radiators and is normally marked with numbers or symbols.Explore ServicesStill not sure which term fits?
Describe the room, fixture and visible change instead. You do not need to name a part correctly to send a useful plumbing enquiry.