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Frozen pipes: how to prevent them and thaw them safely
A frozen pipe can split and flood a home when it thaws. Here is how to keep pipes from freezing, how to thaw one safely, and what to do if one bursts.
The short answer
No water from a faucet in freezing weather? Keep the faucet open and warm the pipe with a hair dryer, heating pad or space heater – never an open flame. If a pipe has burst, shut off the main water valve and call a plumber. To prevent freezing, drip faucets on exposed pipes, open cabinet doors under sinks, and keep the heat at 55 degrees F or higher if you are away.
Which pipes freeze
The American Red Cross lists the pipes most at risk: supply pipes in unheated areas such as basements, crawl spaces, attics, garages and kitchen cabinets, and pipes on exterior walls. Outdoor hose bibs and sprinkler lines freeze too.
Before and during a cold snap
- Let cold water drip from faucets served by exposed pipes (Red Cross).
- Open kitchen and bathroom cabinet doors so warmer air reaches the plumbing.
- Keep the garage door closed if water lines run through the garage.
- Remove, drain and store outdoor hoses, and close the inside valves that feed outdoor hose bibs.
- Insulate pipes with pipe sleeves or UL-listed heat tape.
- If you travel, leave the heat on and set no lower than 55 degrees F.
- Know where your main shut-off valve is and how to close it before winter, as the City of Gresham, Oregon advises.
Signs a pipe is frozen
Only a trickle or nothing comes out of a faucet when it is very cold outside. You may see frost on an exposed pipe. If one faucet works and another does not, the freeze is on the line to the one that does not.
How to thaw a frozen pipe safely
- Keep the faucet open, so water can flow as the ice melts (Red Cross).
- Apply heat to the frozen section with an electric heating pad, a hair dryer or a portable space heater kept away from anything flammable.
- Keep heating until full water pressure returns, then check other faucets.
Never use a blowtorch, kerosene or propane heater, charcoal stove or any open flame, the Red Cross warns. Do not use electrical appliances while standing in water.
If a pipe bursts
Shut off the water at the main shut-off valve and open a couple of faucets, the City of Gresham advises. The main is usually along a basement wall near the water meter, or where the supply line enters the building, according to the Missouri Public Service Commission. If water is near outlets or the electrical panel, keep away and turn off power at the panel only if you can reach it safely. Then call a plumber who takes emergency calls, and photograph the damage for insurance.
When to call a plumber
The Red Cross says to call a licensed plumber if you cannot find the frozen section, cannot reach it, or cannot thaw it. Call right away for a burst or leaking pipe, and before winter if pipes in an unheated space keep freezing – rerouting or insulating them is a lasting fix.
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Questions
How do I know if my pipes are frozen?
In freezing weather, a faucet gives only a trickle or no water at all. You may also see frost on exposed pipes.
Should I let my faucets drip to prevent frozen pipes?
Yes. The American Red Cross advises letting cold water drip from faucets served by exposed pipes in very cold weather.
Can I use a hair dryer to thaw a frozen pipe?
Yes. The Red Cross lists an electric heating pad, a hair dryer or a portable space heater. Never use an open flame, and keep the faucet open while you thaw.
What temperature should I leave the heat at when I travel in winter?
The Red Cross says to leave the heat on and set no lower than 55 degrees F.
Related guides
Sources
Facts and figures in this guide come from these official and manufacturer sources, checked October 2026:
- American Red Cross – Frozen pipes
- City of Gresham, OR – Winter water pipes
- Missouri Public Service Commission – Protect water pipes
Updated October 2026 by the Plumbers Pages editorial team. General information for homeowners, not professional advice – codes and equipment differ, so follow your product’s manual and local rules. When gas, electricity, sewage or anyone’s safety is involved, call 911, your utility or a licensed plumber. How we write our guides · Plumbing glossary
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