A stopcock (or stop tap) is a valve that shuts off the cold water supply to your home. It is the first thing you reach for when a pipe bursts or a leak starts, yet many people have never located theirs. Taking five minutes now to find it, confirm it turns, and tell everyone in the household where it is can save a great deal of damage later. Here is where to look and how to be sure you have found the right one.
What a stopcock looks like
A typical internal stopcock is a small brass or chrome valve fitted onto the pipe that brings mains cold water into your home. It usually has a round, wheel-shaped handle or a lever, and sits on a pipe roughly 15 to 22mm across. It can look a little like an outside tap but without a spout, and it may be dull or slightly tarnished if it has not been used in years. Where there are two taps close together, the stopcock is on the rising main, the pipe coming up from the floor or through an external wall.
Common locations in a UK home
In most UK homes the internal stopcock is:
- Under the kitchen sink, by far the most common spot, tucked at the back of the cupboard near where the mains pipe enters.
- In a downstairs cloakroom or utility room, often near where the supply pipe comes through the floor or wall.
- Under the stairs or in a hallway cupboard, sometimes beside the meter or near the front door.
- In a cellar or basement, on the incoming pipe, frequently close to the point of entry.
- In a garage, where the supply enters through the garage wall in some newer homes.
If you cannot find an internal stopcock at all, there is almost always an external stop valve at the boundary of the property. Our guide on how to turn off your water supply explains both the internal and external valves and how to operate them.
Flats and older properties
In a flat, the stopcock may be inside a kitchen or bathroom cupboard, in a service riser cupboard on the landing, or in a communal area. Your freeholder, managing agent or neighbours may know. In older houses, pipework has sometimes been altered over the years, so the valve can be in an unexpected place, such as behind a kitchen kickboard or inside an airing cupboard. If the valve you find is stiff, corroded or leaks when you turn it, it is worth having it checked; a faulty one can be put right with a stopcock repair or replacement so it is dependable when it matters.
Test it works, before you need it
Finding the stopcock is only half the job; you need to know it actually shuts the water off. Turn it clockwise until it stops, then run a cold tap. The flow should slow and stop. Turn it back anticlockwise slowly to restore supply. Do this gently a couple of times a year so it does not seize. If it will not move, do not force it to the point of damaging the valve or pipe. A stopcock that fails during a genuine emergency is one of the reasons a small leak becomes a bigger problem, so a reliable valve is a sensible early step in preventing common plumbing emergencies.
Label it and tell the household
Once you have found and tested the stopcock, tie a small luggage label to it or mark the cupboard so anyone can find it in a hurry, including tenants, housesitters or family members. In an emergency, seconds count, and a labelled stopcock means nobody has to hunt for it with water pouring in. If the worst does happen and a pipe lets go, knowing where your stopcock is turns a potential disaster into a manageable problem; our step-by-step guide on what to do when a pipe bursts takes it from there.
This guide offers general information for UK households and is not a substitute for professional advice. If you are unsure or a valve is damaged, call a plumber rather than forcing it.