If a water pipe has burst, turn off the water at your internal stop tap (usually under the kitchen sink, turn clockwise). If water is near any electrics, switch off the electricity at the fuse box only if it is safe and dry. Then open the cold taps to drain the system, catch and contain the water, and call for help.
A burst water pipe is one of those moments that gets the heart racing. Water where it should not be, perhaps coming through a ceiling or pooling on the floor, and the clock ticking on the damage. Try to stay calm. The job in the first few minutes is simple: stop the flow, make things safe, and limit the mess. This guide walks through exactly what to do right now, what tends to cause a burst, and how a hidden or underground burst is found without tearing the place apart.
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What to do right now
Safety comes first, then stopping the water, then limiting the damage. Work through these steps in order.
- Turn off the water at the stop tap. Find your internal stop tap, usually under the kitchen sink, and turn it clockwise to shut off the mains supply. Turn it slowly and do not force it. This is the single most useful thing you can do, so it is worth knowing where yours is before an emergency. WaterSafe and South West Water both recommend every household locates this tap in advance.
- Switch off the electrics if water is near them. If water is dripping near a light, a socket or any wiring, do not touch the fitting or switch. Turn off the electricity at the consumer unit, the fuse box, only if you can reach it safely and your hands and the area are dry. Electrical Safety First advises leaving the power off until a qualified electrician has confirmed it is safe.
- Drain the system. With the stop tap off, open all the cold taps and flush the toilets. This clears the water still sitting in the pipes and eases the pressure, so less escapes from the burst while you sort it out.
- Catch and contain. Put buckets, bowls and towels under the leak, move furniture, electricals and valuables clear, and lift anything off a wet floor.
- Relieve a bulging ceiling, carefully. If water has collected above a ceiling and it is sagging, keep everyone well clear. Only if you are confident and safe, piercing a small hole at the lowest point lets the water drain into a bucket rather than the whole section coming down at once.
- Take photographs and call for help. Record the damage and the date in case you claim. Then get a plumber or a leak detection specialist out. If the burst is hidden or underground and you cannot see where the water is coming from, that is exactly when a specialist earns their keep.
How to find and turn off your stop tap
Your internal stop tap, sometimes called a stopcock, is the valve that shuts off the mains water to your home. It is most often under the kitchen sink, but it can also sit under the stairs, in a downstairs toilet, in a utility room or wherever the supply pipe first comes into the house. To close it, turn it clockwise. If it is stiff from years of standing still, ease it rather than wrench it, as forcing an old tap can break it. If you cannot move it or cannot find it at all, there is usually an outside stop tap near your boundary that the water company can help with. Our guide on how to find the shut-off valve for your water walks through every place to check.
Who is responsible: your pipe or the water company's
It helps to know whose pipe has burst, because that decides who fixes it. As a general rule, you are responsible for the supply pipe, the underground pipe that runs from your boundary into the property, along with all the plumbing inside the home. The water company looks after the water main running under the street and, commonly, the communication pipe up to the boundary. In the South West Water area, covering Cornwall and Devon, this is the standard split, confirmed by both South West Water and the Consumer Council for Water.
So a water main leak in the road is the water company's problem to repair, while a burst on your supply pipe or inside the house is normally yours. If you are not sure which side of the boundary the leak is on, or you have had a letter saying your usage has jumped, our article on what to do when South West Water says you have a leak explains the next steps.
What causes a pipe to burst
Pipes burst for a handful of common reasons. Knowing which one you are dealing with often points to where the damage is.
| Cause | What is going on |
|---|---|
| Freeze and thaw | The classic winter burst. Water expands as it freezes and the pressure splits the pipe. The crack often stays sealed by ice, so the leak only appears when it thaws. Pipes in lofts, garages and outside walls are most at risk. |
| Corrosion and old pipes | Older steel, iron or early plastic pipes weaken over the years. Corrosion thins the pipe wall until it gives way, and ageing joints and fittings work loose, especially on long-buried supply pipes. |
| High or fluctuating pressure | Too much mains pressure, or pressure that surges, stresses pipes and joints. Over time a weak spot or a tired fitting fails under the strain. |
| Ground movement | Settlement, nearby digging, tree roots and shifting soil can put a buried supply pipe under load until it cracks. Heavy traffic over a shallow pipe can do the same. |
| Wear, knocks and bad joints | A poorly made joint, an accidental knock during other work, or simple vibration and age can all start a slow leak that grows into a burst. |
Visible burst or hidden burst
Not every burst is obvious. It is worth knowing which kind you have, because they are dealt with very differently.
A visible burst is the one you can point at: a split pipe under the sink spraying water, a joint dripping in the airing cupboard, a soaked patch of carpet right by a radiator. Here you can see the source, get a bucket under it, and a plumber can usually go straight to the repair.
A hidden or underground burst is sneakier. The pipe might be buried under a solid floor, run through a wall, sit beneath the garden, or be a heating pipe under the floorboards. You see the symptoms, a damp patch, a drop in pressure, a hissing sound, a water bill or meter creeping up, an unexplained warm patch on the floor, but not the leak itself. A burst pipe under the floor can travel a long way along a joist or through the screed before the water surfaces, so the wet spot is often nowhere near the actual split. Chasing the symptom and digging or lifting at the obvious place tends to waste time and cause damage for nothing.
How leak detection pinpoints a hidden burst
This is where non-invasive leak detection comes in. The aim is to find the exact point of the burst before anything is dug up or opened, so the repair is a small, targeted job rather than a guess. A specialist combines several methods.
- Acoustic detection. Sensitive ground microphones and correlators pick up the sound a pressurised leak makes as water escapes, which is one of the best ways to locate a buried supply pipe or water main leak under a path or garden.
- Thermal imaging. A thermal camera reads small temperature differences across a floor, wall or ground surface, so a hot heating leak shows as a warm trail and a cold supply leak as a cool one, mapping it back to the source.
- Tracer gas. A safe gas is fed into the emptied pipework and rises to the surface at the exact point it is escaping, which pinpoints slow or intermittent bursts that are otherwise very hard to find.
- Moisture meters. These confirm how far the water has tracked and where it is wettest, narrowing down the real source rather than the spot where it happened to surface.
Put together, these tools turn a dig-and-hope job into a precise one. For an underground burst, that often means one small excavation at the confirmed leak instead of trenching the whole supply line. Our mains water leak detection service covers exactly this, and for leaks out in the garden or driveway our underground water leak detection service explains how the buried pipe is traced.
Insurance and trace and access
A burst pipe and the resulting water damage is often covered by home insurance under sudden escape of water, though cover always varies, so check your own policy. The part many people miss is trace and access cover. This pays to find a hidden leak and to make good the damage caused by getting to it, for example lifting a section of floor or chasing into a wall. According to the Association of British Insurers, these limits typically start around five thousand pounds, though they differ between insurers.
Trace and access cover does not usually pay to repair the pipe itself, only to locate it and put right the access damage. To claim, insurers look for evidence: photographs of the damage and a professional leak detection report that confirms the leak was found and where. Keeping that documentation makes a claim far smoother.
Frequently asked questions
What is the first thing to do when a water pipe bursts?
Turn off the water at your internal stop tap, usually under the kitchen sink, by turning it clockwise. If water is near any electrics, switch off the electricity at the fuse box only if it is safe and dry to do so. Then open the cold taps to drain the system, catch what you can, and call for help.
Where is my internal stop tap?
The internal stop tap is most often under the kitchen sink, but it can also be under the stairs, in a downstairs toilet, in a utility room or near where the supply pipe enters the house. Find it before you ever need it. Turn it clockwise to shut the water off, slowly, and do not force a stiff one.
Who is responsible for a burst pipe, me or the water company?
As a rule, you are responsible for the supply pipe that runs underground from your boundary into the home, plus all the plumbing inside it. The water company looks after the water main in the street. In the South West Water area this is the standard split, so a burst on your side of the boundary is normally yours to sort.
Why do water pipes burst in winter?
When water freezes it expands, and the pressure can split the pipe. The crack often stays sealed by ice, so the burst only shows once it thaws and water starts to escape. Pipes in cold spots, such as lofts, garages and outside walls, are most at risk, which is why lagging them helps.
Can a burst pipe under the floor be found without digging everything up?
Usually, yes. Non-invasive leak detection uses thermal imaging, acoustic listening, tracer gas and moisture meters to pinpoint a hidden or underground burst, so any digging or opening up is aimed at one small spot. That avoids lifting a whole floor or excavating the full length of a garden to find it.
Will my insurance cover a burst pipe?
Many home policies cover sudden escape of water from a burst pipe, and trace and access cover pays to find the leak and make good the damage caused by reaching it, with limits that typically start around five thousand pounds. Cover varies, so check your policy, take photographs and keep a professional leak report as evidence.
Burst pipe you cannot find? We will trace it fast
We locate hidden and underground bursts across Cornwall and Devon using acoustic detection, thermal imaging and tracer gas, so we find the exact spot without digging up the whole garden or floor. Fast response, minimal damage, and the insurer-ready report if you need to claim.
Call Dickie on 07822 025 911 No Find, No Fee on residential leak detection (subject to terms)