If water is escaping, the first thing to do is turn off the supply at the stopcock (the main valve that controls cold water into your home). Stopping the flow buys you time and limits damage; everything else comes after. If the leak is small and you can catch it in a bucket, you may have room to think. If water is gushing or spraying near electrics, treat it as urgent.
First moves when water is escaping
Act in a sensible order. The aim is to cut the supply, reduce pressure, and stay safe around electricity.
- Turn off the stopcock to stop more water entering the system.
- Open the cold taps in the kitchen and bathroom to drain the pipes and relieve pressure. This empties water that is already in the system so it stops feeding the leak.
- If the leak is near sockets, switches or a fuse board, switch off the electricity at the consumer unit (fuse box) before you go near it.
- Turn off the boiler or central heating if hot water is involved, as scalding is a real risk.
- Move valuables, electricals and soft furnishings out of the way.
Once the flow stops, you can assess calmly. A pipe that has stopped dripping after the stopcock is closed is usually safe to leave until a plumber attends. One that keeps running may be fed from a tank rather than the mains.
Finding and using the stopcock
If water is escaping, the first thing to do is turn off the supply at the stopcock (the main valve that controls cold water into your home).
The internal stopcock is most often under the kitchen sink, but it can also sit in an airing cupboard, a downstairs toilet, under the stairs, or near where the supply pipe enters the building. In flats it may be in a hallway cupboard or a shared riser. It is worth locating it before an emergency, not during one.
To close it, turn the handle clockwise until it stops. If it is stiff from years of disuse, work it gently rather than forcing it, as old brass valves can shear. Once a year, turning it off and on a couple of times helps keep it free.
If the internal valve will not move or has seized, there is usually an external stopcock at the boundary of the property, often under a small metal or plastic cover in the pavement or driveway. This typically needs a stopcock key, a long T-shaped tool. The pipework from that point to the meter is generally the water company's responsibility; the pipe inside the boundary is usually the homeowner's.
Telling a minor drip from an urgent burst
Not every leak needs an emergency call-out. The difference is about volume, location and what the water can reach.
Signs you can probably manage for a short while:
- A slow drip you can catch in a container.
- A weep from a visible joint under a sink that slows or stops once the stopcock is closed.
- A damp patch that is not spreading.
Signs that point to an urgent burst pipe needing a plumber promptly:
- Water spraying, gushing, or pooling faster than you can mop.
- Water coming through a ceiling, or staining and bulging plaster.
- Anything near electrical fittings or the fuse board.
- No water at the taps combined with sounds of running water somewhere you cannot see.
- A drop in pressure or a hot water cylinder overflowing.
A burst is more likely after a cold snap, when frozen water expands inside a pipe and splits it. The split may only show when the ice thaws, so a sudden leak during a mild spell after frost is a common pattern.
Tracing a hidden leak
Some leaks never appear at the source. Water travels along joists, under flooring and behind walls before it emerges, so the damp patch is often some distance from the actual fault. Leak detection is the process of narrowing down where the water is really coming from.
A few clues help. A rising water bill with no change in use suggests water is escaping somewhere. The water meter is a simple test: turn off every tap and appliance, note the reading, and check again after an hour. If it has moved, water is leaking somewhere on the supply.
Listen for running or trickling when the house is quiet. Check obvious culprits first: under sinks, around the boiler, behind the washing machine and dishwasher, and around radiator valves. Damp, musty smells, peeling paint, warm spots on a floor, or persistent mould can all signal a hidden leak.
If the source stays out of sight, a plumber may use specialist equipment such as acoustic listening devices, thermal imaging or moisture meters to pinpoint it without tearing up floors at random. This is worth asking about before any walls or floors are opened up.
Limiting damage while you wait for help
Once the supply is off, the priority shifts to protecting the building and contents. Standing water and damp cause more long-term harm than the leak itself, so the quicker the area dries, the better.
- Mop or soak up standing water and lift rugs and curtains clear of it.
- Place buckets or towels under any continuing drip.
- If water is collecting in a ceiling, a small hole made with a screwdriver at the lowest bulge can release it in a controlled way rather than letting the ceiling collapse. Put a bucket underneath first.
- Open windows and use a fan or dehumidifier to start drying once the leak has stopped.
- Photograph the damage before clearing up, as this helps with any insurance claim.
It is sensible to contact your home insurer early. Many policies cover sudden water damage, sometimes called "escape of water", and some insurers want to be notified before major drying or repair work begins. Keep notes of what happened and when.
While waiting, avoid switching electrics back on near wet areas, and keep children and pets away from any standing water that may have reached cabling. A measured, methodical response in the first few minutes usually does more to limit damage than rushing.