How to Turn Off Your Water Supply

Your stopcock is almost always under the kitchen sink, fixed to the incoming cold water pipe where it enters the property. In older London terraces and Victorian conversions across Tower Hamlets, Hackney and Islington, it can also sit under the stairs, in a hallway cupboard, or behind a low-level bath panel if the pipework was rerouted at some point.

Look for a small valve with a lever, wheel, or a slotted screw-style head on a short section of pipe close to the floor. This is the internal stopcock, and it controls the entire property's water supply — turning it off is the single fastest way to stop a leak or burst pipe from getting worse. For a full photo-led walkthrough of every place a stopcock hides in London properties, see our dedicated stopcock guide.

The internal stopcock is inside your property and is what most people mean by "the stopcock" — it's the one to try first. The outside stopcock sits under a small cover near the boundary of the property or under the pavement, and controls the supply before it even reaches your internal pipework, so it's your backup if the internal one is stuck, missing, or doesn't fully stop the flow.

The water meter valve, where fitted, is usually housed in the same underground chamber as the outside stopcock or in a meter box on an external wall, and also isolates the mains supply. In practice, most East London homes only need the internal stopcock — the outside valve and meter are there as a second point of control when something's gone wrong closer to the street.

Lift the small metal or plastic cover set into the ground near your boundary, footpath, or front driveway, then turn the valve inside clockwise using a stopcock key or a long-handled spanner. These covers are often stiff or covered by grass or paving slabs in London terraces, so a torch and a bit of digging around the edge helps if you can't spot it straight away.

You'll usually only need the outside stopcock if the internal one is broken, seized, or if you can't locate it at all — for most day-to-day leaks, the internal stopcock under the sink is quicker and just as effective.

Start with the cupboard under your kitchen sink or the airing cupboard, since many purpose-built flats across Tower Hamlets, Canary Wharf and Shoreditch have their own individual stopcock inside the flat. If nothing's there, the shut-off is likely in a communal riser cupboard on the landing, in a shared utility room, or in the building's plant room — these are usually locked, so speak to your managing agent, concierge, or freeholder about access.

If several flats share one riser and you turn off a valve there, warn your neighbours first, since you may cut their water off too. For a leak that's actively spreading and you can't get to the communal valve quickly, isolating your own flat's internal stopcock (if you have one) buys time until a plumber or the building manager can get to the shared supply.

Follow these steps in order — most leaks are fully isolated by step two, with the later steps as backup if the main stopcock doesn't do the job.

1. Find the stopcock. Look under the kitchen sink first, then check the bathroom, airing cupboard, utility cupboard or under the stairs. It's usually a small brass or plastic valve on the incoming pipe, often near where it enters through the floor or an external wall.
2. Turn the handle clockwise. Turn the lever or wheel clockwise (the same way you'd tighten a screw) until it stops. Most stopcocks only need a half to full turn to cut the supply off completely.
3. Open a downstairs tap to confirm. Run a cold tap, ideally the kitchen tap, and let it drain. If the flow slows to a trickle and stops, the water is off; if it keeps running steadily, the stopcock isn't fully shutting the supply.
4. Check the outside stopcock if needed. If the internal stopcock is stuck, missing, or not stopping the flow, find the outside stopcock — usually under a small metal or plastic cover near the boundary of the property, footpath, or driveway — and turn it clockwise with a stopcock key or long-handled spanner.
5. Isolate the header tank if you have one. If your home has a loft header tank feeding the cold water system, close the isolation valve on the tank's outlet pipe too, otherwise gravity will keep feeding water to the leak even with the mains stopcock shut.

Call a plumber immediately if the stopcock won't turn, water keeps flowing after you've shut it off, or you can't locate any isolation valve while water is actively damaging your home. RenoPlumb covers Tower Hamlets, Hackney, Islington, Newham, Southwark, Canary Wharf and the wider East and Central London area from our E1 base, and we're Gas Safe registered for any job that also involves a boiler or gas appliance.

Water still flowing? Call 07460 824073 now — see our emergency plumber page for what to expect and how quickly we can reach you.

Freeing a stuck stopcock, fitting a new one, or tracing a supply that won't isolate properly varies depending on access and what's actually wrong with the valve, so we don't quote a figure without seeing the job first. Every visit starts with a free, no-obligation quote for most jobs, whether it turns out to be a five-minute fix or a full valve replacement.

For a broader sense of how we price different plumbing jobs across London, see our pricing page.

Need this fixed by someone local? See our page for a plumber in East London for borough-specific coverage and response times.