Stop tap
In plumbing · also called Stopcock
A valve that shuts off the cold water supply to a building or to part of it. Most homes have an internal stop tap where the supply pipe comes in, often under the kitchen sink, and another outside near the boundary, usually under a small cover. Knowing where the internal one is, and checking that it turns, is the first step in dealing with a leak.
Using Stop tap in a plumbing system
Updated
A distinction worth remembering
A main stop tap controls a supply to a building or part of it; a service valve usually controls a smaller part. Stored water or separate supplies can remain available after a valve is closed, so position alone does not establish what it isolates.
Questions to take further
- Will closing one valve always turn off every tap?
- No. Stored supplies, separate feeds and shared arrangements can change what remains available. Identify the system and confirm the effect rather than relying on the valve's location alone.
Sources
- Skills England: plumbing and domestic heating technician — The systems, materials, planning and customer responsibilities in the England occupational standard.
Where Stop tap fits in the learning path
The Cold Water Basics section covers these topics:
- The Incoming Water Supply
- Cold Water Storage and Backflow
Read, practise, return
1. Read it in context
- The Incoming Water SupplyCold Water Basics
- Isolating and Draining DownIsolation, Hot Water Safety and Simple Repairs
2. Try recalling, then explore practice
Use the memory prompt below to connect the vocabulary.
3. Return to the meaning
After reading or practising, explain the idea in your own words, then check what you remembered.
Recall a related term
Which term fits this definition? Say it to yourself, then reveal it. This is a memory prompt, with no score or saved result.
A small valve on the pipe to a single tap, cistern or appliance, so that one outlet can be turned off without shutting off the whole house. Many are quarter-turn: the slot or lever lines up with the pipe when the valve is open and sits across it when closed. Turning one off and then opening the outlet shows whether it has worked.
Service valve
Read the Service valve entryCompare related terms
Open a meaning to compare its role with Stop tap, or follow its full entry.
Service valve — Isolating valve
A small valve on the pipe to a single tap, cistern or appliance, so that one outlet can be turned off without shutting off the whole house. Many are quarter-turn: the slot or lever lines up with the pipe when the valve is open and sits across it when closed. Turning one off and then opening the outlet shows whether it has worked.
Read the Service valve entryIsolation
In plumbing, turning off the water to the part of a system you are working on, then proving it is off by opening an outlet and checking that the flow stops. Isolate as close to the job as possible, with a service valve where there is one and the stop tap where there is not, and drain the section down before opening it up.
Read the Isolation entryBefore you start: some plumbing work is regulated or notifiable
Some water fittings work needs notice to, and consent from, the water supplier before it starts. Check the rules where you live.
Gas work is for competent workers covered by a Gas Safe registered business in Great Britain. Northern Ireland has separate gas regulations. Do not work on gas pipes or appliances yourself.
In England, installing an unvented hot-water system over 15 litres is notifiable building work: use a competent installer registered with a competent-person scheme, or tell building control before work starts. Leave this work to a suitably skilled person.
Wales, Scotland and Northern Ireland have their own water and building rules; check which apply before work starts. Electrical connections belong with an electrician.
This guide does not qualify you or make you competent, approved or registered for plumbing, gas or unvented work.
A definition is a start. Using it in a real question is where it sticks.