If you turned a tap this morning and got a trickle or nothing at all, and it is below freezing, you almost certainly have ice in a pipe. The pipe is probably still intact. What happens in the next hour decides whether it stays that way.
What to do
- Leave the tap open. Both hot and cold on the affected fixture. Running water, even a trickle, carries heat and gives melting ice somewhere to go. A closed system is how pressure builds.
- Find the frozen section. Follow the pipe from the dead tap back towards where it enters the house. It will be the coldest stretch — an outside wall, a crawl space, an unheated basement, a garage. Frost or bulging on the pipe is a giveaway.
- Warm it gently, starting at the tap end. A hairdryer, a heat lamp, a space heater, or towels soaked in hot water. Work from the tap towards the frozen section so meltwater has an open route out.
- Keep going after it flows. Ice further along the pipe is common. Run the tap for several minutes.
- Know where your main shut-off is before you start. If the pipe has split, you will have seconds, not minutes.
Never use an open flame. No blowtorch, no propane heater aimed at a pipe. It is a leading cause of house fires in cold snaps, it can boil water inside a closed pipe into steam, and on plastic pipe it does damage you will not see until later.
If a pipe has already burst
- Shut off the water at the main. Before anything else, including looking at the damage.
- Turn off electricity to any area with water in it, at the breaker, if you can reach it without standing in water.
- Open taps to drain the system down so the remaining water leaves through a tap rather than the split.
- Photograph everything before you clean up. Insurers ask, and the photograph taken while it is bad is the useful one.
- Call a plumber, then call your insurer. Most policies cover sudden pipe bursts. Many exclude damage from a system that was left unheated, which is a distinction worth knowing before you describe the week.
Drying out is the part people underestimate
Water behind drywall and under flooring does not evaporate on its own, and mold begins in a day or two. Getting air moving and the wet material out early is what separates a repair from a much bigger repair. This part is not specialist work — moving furniture, pulling up soaked carpet, running fans, hauling ruined material — and it is exactly what a couple of locals with a van can do the same day.
Stopping it happening again
- Insulate the pipes you can reach. Foam sleeves are inexpensive and take an afternoon in a crawl space or garage.
- Disconnect hose bibs before the first freeze and shut off their interior valve. An attached garden hose is one of the most common causes of a burst outdoor line.
- Open cabinet doors under sinks on outside walls during a cold snap, so household heat reaches the pipes.
- Do not let the house drop below about 55°F when you are away. The saving on heating is not close to the cost of one burst pipe.
- Know and label the main shut-off. If somebody else in the house could not find it in the dark, it is not really known.
Every item on that list is an ordinary job you can hire someone local for, and all of it is cheaper in October than in January.
Frequently asked questions
How do I thaw a frozen pipe?
Leave the tap open, find the coldest stretch of pipe between the tap and where the line enters the house, and warm it gently with a hairdryer, heat lamp or hot towels — working from the tap end towards the ice so meltwater has somewhere to go. Never use an open flame: it is a leading cause of house fires in cold snaps and can turn trapped water into steam.
Will a frozen pipe always burst?
No. Many thaw without splitting. The risk rises the longer it stays frozen and if the tap is closed, because a sealed section has nowhere to release pressure. Leaving the tap open is the single most useful thing you can do while you work on it.
What do I do if a pipe has burst?
Shut the water off at the main before anything else, cut power to any flooded area at the breaker if you can reach it safely, open taps to drain the system, and photograph everything before cleaning up. Then call a plumber, and your insurer — most policies cover a sudden burst, though many exclude damage from a home left unheated.
How do I stop pipes freezing again?
Insulate exposed pipes in crawl spaces, garages and outside walls, disconnect garden hoses and shut off their interior valves before the first freeze, open cabinet doors under sinks on outside walls during a cold snap, and never let the house fall below about 55°F when you are away.