If a pipe bursts, turn off your water supply at the internal stopcock straight away, then open the cold taps to drain the system. That single action — stopping the flow at the mains — does more to limit damage than anything else. Once the water is off, you can deal with the leak, the mess and the repair in a calmer order.
The first steps when a pipe gives way
Find the stopcock (also called a stop tap) and turn it clockwise until it stops. This shuts off the cold water entering the house. Then open every cold tap, starting with the lowest in the property, so water still sitting in the pipes drains out rather than continuing to pour through the break.
If water is near light fittings, sockets or the consumer unit (the fuse box), switch off the electricity at the mains before going anywhere near it. Wet electrics are a serious hazard, and water tracking through a ceiling can reach wiring you cannot see. Move furniture, soft furnishings and anything valuable out of the affected area, and put down towels or a bucket to catch what is still dripping.
If a flooded ceiling is bulging, it is holding water that needs to come down in a controlled way. Place a bucket beneath the lowest point and, only if you can do so safely, pierce a small hole to let it drain, rather than waiting for the whole section to collapse at once. Once the immediate flow is under control, take photographs of the damage before you start clearing up — these are useful if you later make an insurance claim.
Finding and using your stopcock
If a pipe bursts, turn off your water supply at the internal stopcock straight away, then open the cold taps to drain the system.
The internal stopcock is the valve that controls all the cold water coming into your home. In most houses it sits under the kitchen sink, but it may also be in a downstairs cloakroom, a utility room, an airing cupboard, under the stairs or near where the supply pipe enters the building. It is worth locating it now, while there is no emergency, and checking that it turns freely.
To close it, turn the handle clockwise. Stopcocks that have not been moved for years can seize, so if yours is stiff, do not force it to the point of snapping the spindle. A gentle back-and-forth motion sometimes frees it; a small amount of penetrating oil on the thread can help over time. If it will not budge in an emergency, you may be able to stop the supply at the external stop valve, which is usually under a small metal or plastic cover near the boundary of the property and often needs a long-handled key to reach.
Homes with a cold water storage tank in the loft will keep feeding the taps and toilet cistern from that tank even after the mains stopcock is closed, so opening the taps to empty it down is part of stopping the flow. Knowing whether your system is fed directly from the mains or from a stored tank tells you what to expect when the water keeps running for a while.
Thawing a frozen pipe without causing damage
A frozen pipe shows itself as no water, or only a trickle, from a tap during cold weather, often after a hard overnight frost. The risk is that the ice expands and cracks the pipe, with the leak only becoming obvious when it thaws. If you suspect a freeze, close the stopcock first so that any hidden split does not flood the house the moment the ice melts.
Thaw the pipe gently and slowly. Apply warmth to the frozen section using a hot water bottle, towels soaked in warm water, or a hairdryer on a low setting, working from the tap end back towards the frozen part so meltwater has somewhere to go. Never use a naked flame, a blowtorch or a heat gun on full power — rapid, intense heat can crack the pipe or, in the case of plastic fittings, damage the joints.
Open the nearest tap before you start so you can see when flow returns and to relieve pressure as the ice melts. Frozen pipes are most common in unheated spaces: lofts, garages, outbuildings and against exterior walls. If you cannot reach the frozen section, or it lies behind a wall, that is the point to stop and seek professional help rather than risk making it worse.
Keeping pipes from freezing through the winter
Most freeze damage is preventable with a little preparation before the cold sets in. Lagging — foam insulation sleeves that slip over pipework — is the single most effective step, especially on pipes in lofts, garages and any unheated area. Water tanks and the back of outside taps benefit from insulation too.
- Fit lagging to exposed pipes and insulate any cold water tank.
- During a cold snap, leave the heating on a low background setting rather than off, so the house never drops below freezing inside.
- If you go away in winter, either keep the heating ticking over or drain the system down.
- Fix dripping taps and seal draughts near pipework, as moving air and standing water both raise the freezing risk.
- Make sure everyone in the household knows where the stopcock is and which way it turns.
Outside taps are a common weak point. Isolating and draining them before the first frost, where there is a separate valve to do so, removes the water that would otherwise freeze and split the pipe.
When the job needs an emergency plumber
Call an emergency plumber when the water will not stop after the stopcock is closed, when a leak is reaching electrics, or when a burst is somewhere you cannot safely reach. The same applies if a frozen pipe will not thaw, if you find a split once the ice melts, or if a soldered or pushed-fit joint has failed and needs proper repair rather than a temporary patch.
For lower-grade problems — a slow drip you have contained, a tap that has stopped working in the cold — it may be reasonable to wait for a standard appointment, which usually costs less than an out-of-hours call-out. When you do call, it helps to describe what has happened, whether the water is off, and where the problem is, so the plumber arrives with the right parts. Keeping a note of your insurer's emergency helpline alongside the plumber's number means you are not searching for both at once when something goes wrong.