Burst pipe at 3am: the first five minutes

A leak is the one household emergency where the first five minutes matter more than everything that follows. A plumber is forty minutes away at best. The water is arriving now.

So the order below is deliberate. Nothing about phoning anyone appears until step four.

1. Turn the water off

Find the internal stopcock and turn it clockwise.

It is most commonly under the kitchen sink. Other frequent places: a downstairs bathroom or cloakroom, under the stairs, in an airing cupboard, near the front door in a flat, or in a garage or utility room.

It will not stop instantly. There is still water in the pipes above you, and it takes a few minutes to run through. Do not decide the stopcock has failed after ten seconds.

If the internal stopcock is seized or you cannot find it, there is an outside stop tap controlling the supply before it enters the property — usually under a small metal or plastic cover in the path, pavement or driveway, often near the water meter. It normally needs a stopcock key, though a long screwdriver and patience have got a lot of people through the night.

2. Drain the system

Once the supply is off, open all the cold taps and flush the toilets. This empties the pipework quickly, so whatever is still leaking has less to leak.

3. Protect the boiler and the heating

Turn the heating off, and switch the boiler off at its spur or programmer. A boiler that fires with no water running through it can damage itself.

Then soak up what you can. Towels, buckets, and anything that keeps water off floorboards and away from the ceiling below. A bucket under a bulging ceiling is worth more than a photograph of a bulging ceiling.

4. Now decide who to ring

Three different phone calls, and people ring the wrong one constantly.

Is the leak outside your property, in the street, or before the stopcock? That is the water company’s problem, and their cost. In most of London that is Thames Water. Their emergency line runs 24 hours — check your supplier by postcode if you are not sure. Thames Water publishes its burst pipe guidance here.

Do you have home insurance or a home emergency policy? Ring the number on the policy before ringing a plumber. Many policies cover escape of water and send their own contractor — and arranging your own can complicate or invalidate the claim.

Do you rent? Ring the landlord or letting agent first, even at 3am. A burst pipe is a repair and it is their responsibility. Leave a voicemail if nobody answers — a timestamped message that you reported it protects you later. Same principle as no heating or hot water.

Only then, a plumber. And at 3am, with the water already off, ask yourself honestly whether this is a 3am job or a 9am job. With the supply isolated and the damage stopped, it is very often a morning appointment at a fraction of the price.

Choosing a plumber without getting stung

The same method as every trade, and it takes two minutes.

• Check the register. WaterSafe is the national accreditation scheme for approved plumbing businesses.
• If gas is involved at all — a boiler, a gas-fired system — the engineer must legally be on the Gas Safe Register. That one is the law, not a preference.
• Get the total in writing before they travel — callout, labour, parts and VAT, by text.
• Pay by card.

Full method in how to check any UK tradesperson in two minutes.

Frozen pipes, which is the other version of this

A pipe that has frozen has not burst yet. It bursts when it thaws.

• Turn the water off at the stopcock before you start thawing anything.
• Thaw slowly — a hot water bottle, warm towels, a hairdryer on low, working from the tap end back toward the frozen section.
• Never use a blowtorch or a naked flame on a pipe.
• Watch that section closely as it thaws. That is when the split shows itself.

The ten minutes that saves you thousands

Do this on a calm afternoon, and it is genuinely the highest-value ten minutes in home maintenance.

1. Find your stopcock. Right now. Go and look.
2. Turn it off and on again to check it is not seized. A stopcock that has not moved in fifteen years will not move at 3am either.
3. Photograph where it is and put the picture in your phone. You will not remember at 3am, and neither will anyone staying in your home.
4. Tell everyone in the household where it is. A house-sitter, a teenager, a lodger — anyone who might be there when you are not.
5. Save two numbers: your water company’s emergency line, and your insurer’s claims line.

Most people find their stopcock for the first time while standing in water. It does not have to be that way.

Sources

• Thames Water — frozen or burst pipes
• WaterSafe
• Gas Safe Register

Checked 27 August 2026.