To find the stopcock, follow the cold mains from where it enters the house. In most homes that is under the kitchen sink. In older Cornish houses and bungalows it is often under the stairs, in a floor void, a porch, garage or outbuilding. If you cannot find it, the outside stop valve near the boundary shuts the whole supply off.
Water is running somewhere it should not be, or you simply want to know before it does, and the cupboard under the sink has a waste trap, a washing machine hose and nothing that looks like a tap. Older Cornish houses are the worst for this. The kitchen has often moved since the water was first put in, extensions have been built over the original entry point, and nobody wrote down where the valve went. This guide works through the places a stopcock hides in a cottage, farmhouse or bungalow, what it looks like, how to use the outside valve when you cannot find the inside one, and why labelling it today is worth five minutes.
What you are looking for
The internal stopcock, also called the stop tap, is the valve that isolates the cold mains to the whole property. It looks like a small brass tap with no spout, with a round handle or a lever, fitted in line on a pipe usually 15 or 22 millimetres across. Older ones are dull brass or painted over. Newer ones are chrome with a red or blue lever. It sits on the pipe that comes up through the floor or through an outside wall, before that pipe splits off to feed anything. If your home has a water meter fitted inside, the stopcock is often next to it.
Turning the handle clockwise closes it. Slowly, and never with force. A valve that has not moved in twenty years can seize, and a snapped handle in the middle of a leak is a worse problem than the leak.
Start where the water comes in
The single most useful clue is the route of the supply pipe. It runs from the boundary, usually the road side, in a fairly straight line to the point it enters the building. Stand at the outside meter or stop valve cover, look at the house, and think about which room is nearest along that line. That room, or the one behind it, is where the stopcock will be. In a terrace in Redruth or Camborne that is often the front room or hallway. In a detached cottage it is whichever wall faces the lane.
Where it hides in older Cornish houses
Work through these in order. Take a torch, because the valve is almost always in the dark.
- Under the kitchen sink. Still the most likely spot. Look at the back wall of the cupboard and low down in the corners, behind the washing machine hoses.
- Under the stairs. Very common in pre-war houses. Check low on the wall at the back, sometimes behind a small hatch, sometimes behind boxes nobody has moved since the last owners.
- In the floor void. Cottages with suspended timber floors often have the valve just below floor level near the front door or the old scullery, reached through a small lift-out board or a brass floor plate. Look for a cut in the boards or a plate that does not match the rest.
- The old kitchen or scullery. If the kitchen has moved, the stopcock did not move with it. A utility room, downstairs loo or larder that used to be the kitchen is a strong candidate.
- The porch or hallway. Where the supply rises straight up inside the front wall, sometimes boxed in behind a panel or hidden by a radiator.
- Garage, lean-to or outbuilding. Farmhouses and rural bungalows frequently bring the mains into a garage or dairy first, with the house fed from there. Check near the outside tap.
- The airing cupboard. Less common, but where a cylinder sits close to the entry wall the valve can be at the base of the pipework there.
- Outside on the wall. Some older properties have the valve in a small box on the external wall, or in a chamber just outside the door.
Bungalows
Bungalows built between the 1950s and 1970s, of which Cornwall has thousands from Bude down to Helston, usually have a solid floor and the mains entering near the kitchen. Where the kitchen has been refitted the valve is often behind the plinth of a base unit or inside a corner cupboard with a carousel in front of it. If a later extension wrapped around the original kitchen wall, the stopcock may now be in the extension’s cupboard rather than the kitchen.
Cottages and farmhouses
Granite and cob cottages often had water added long after they were built, and the pipe took the easiest route through the thick wall, which is rarely where a modern plumber would put it. Expect the valve low on an outside wall, in a floor void, or in a former dairy or wash house. Long private supply pipes across fields are common on farms, and some have an intermediate valve in a chamber partway along, which is worth knowing about when a leak is somewhere between the road and the house.
Flats and converted houses
A house split into flats in Truro or Falmouth may have one stopcock for the whole building in the communal hallway or cellar, with individual isolating valves for each flat that may or may not exist. Ask the freeholder or managing agent, and ask now rather than at midnight with water coming through a ceiling.
Still cannot find it? Use the outside stop valve
Every property has a second shut-off near the boundary, usually under a small square cover marked with a W or the supplier’s name, in the pavement, the drive or the front garden, often in the same chamber as the meter. Up to this valve the pipework belongs to South West Water. From it into the house the supply pipe belongs to you.
Lift the cover, and if the valve is deep in the chamber use a stop tap key, which costs a few pounds from a plumbers’ merchant and is worth keeping by the front door. Turn it clockwise, slowly. Then open a cold tap indoors to drain the pipe. On a long rural supply this can take several minutes. If the outside valve will not move or you cannot find one, South West Water can isolate the supply.
A word on shared supplies. Older terraces and some farm groups have several houses off one pipe, so the outside valve you find may not be yours alone. If turning it dries your neighbour’s taps as well, you have your answer, and it is worth agreeing with them how a leak would be handled before one happens.
Why this matters more than it seems
The first ten minutes of a burst pipe are spent either turning the water off or hunting for the valve. The difference between those two is the difference between a mopped floor and a replaced ceiling. It matters more in a holiday let or second home, where the person on site may be a cleaner or a guest who has never seen the house before, and in an older house where a slow leak from a hidden joint can run for weeks. If your water bill has jumped and you cannot see why, the stopcock is also the first tool in the meter test, which our guide on an overnight water meter leak test explains.
If you have shut the water off and the damp is still spreading, or the meter turns with the stopcock open and every tap closed, the leak is on the pipework somewhere you cannot see. A water leak detection survey locates it without opening floors on a guess, and our guide to what happens during a leak detection survey sets out how the visit runs.
Label it now
Once you have found it, do four things while you are there.
- Turn it. Close it fully, check the taps stop, then open it fully and back off half a turn so it does not seize in the open position. Do this twice a year.
- Label it. A luggage tag on the pipe or a note inside the cupboard door reading “mains water off, turn clockwise” helps a guest, a cleaner or a family member.
- Photograph it. Keep the picture on your phone and, for a holiday let, in the welcome folder with the location written out.
- Clear the route. If the valve is behind a carousel unit or a stack of boxes, move what you can. If it is genuinely unreachable, ask a plumber to fit a new lever valve somewhere accessible.
We provide leak detection across Cornwall, and knowing where your stopcock is turns a leak, found or not yet found, into a problem you are in control of.
Frequently asked questions
Where is the stopcock usually in an old house?
Follow the mains from the road side of the property. In older houses it is often under the stairs, in a floor void near the front door, in the room that used to be the kitchen or scullery, or in a garage or outbuilding where the supply enters first. Under the kitchen sink is still worth checking first.
What does a stopcock look like?
A small brass tap without a spout, fitted in line on the cold mains pipe, with a round wheel handle or a lever. Older ones are dull brass and often painted. Newer ones are chrome with a coloured lever. It sits before the pipe branches off to anything else, and is often next to an internal water meter.
Can I turn off the outside stop valve myself?
Yes, in an emergency. It is under a small cover near the boundary, often with the meter. Use a stop tap key if it is deep, turn it clockwise slowly and never force it. If it will not move or you cannot find it, South West Water can isolate the supply for you.
My stopcock is seized. What should I do?
Do not force it or use a longer lever, because old handles snap. Try penetrating oil and gentle back and forth movement over a day. If it still will not turn, use the outside stop valve when you need to isolate, and have a plumber replace the valve with a modern lever type.
Does turning the stopcock off stop a leak?
It stops mains water feeding the leak, which stops most supply and cold water leaks. A heating system leak is separate and needs the boiler isolated. A leak on the supply pipe between the boundary and the house is before the internal stopcock, so it carries on until the outside valve is closed.
Water off and still damp?
If the stopcock is closed and the damp keeps spreading, or the meter turns with every tap off, the leak is on pipework you cannot see. We pinpoint hidden leaks across Cornwall and leave you an insurance-ready report.
