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Pipes & pumps

Frozen Pipes: How to Thaw Them Safely and Stop Them From Bursting

A frozen pipe is a warning, not yet a flood. Most bursts happen because pressure builds behind the ice, so the order in which you do things matters more than how fast you do them.

By Household Atlas Editors Updated 4-minute read 3 sources

Quick answer

If a faucet gives only a trickle in freezing weather, a pipe feeding it is probably frozen. Open that faucet, find the cold section (usually along an outside wall, in a crawl space or where the water line enters the house) and warm it with a hair dryer, heating pad or towels soaked in hot water. Never use an open flame. If you see a crack or leak, shut off the main water valve and call a plumber.

Difficulty
Easy DIY
First sign
A trickle, or nothing, from one faucet
Never use
Torches, propane or kerosene heaters, open flames
Away from home
Keep the heat at 55°F or higher
Technician job
Burst pipes, pipes inside walls you cannot reach
On this page

Water is unusual: it expands as it freezes. In a pipe, that does not usually burst the pipe at the ice itself. The ice forms a plug, and as more water freezes behind it, pressure climbs in the trapped section between the plug and a closed faucet. The pipe often splits there, in a stretch with little or no ice. That is why the two most useful things you can do are keep water moving and keep a faucet open.

If a pipe is frozen right now

  1. Open the faucet the frozen pipe feeds.

    Turn on both hot and cold. An open faucet relieves pressure, and as the ice softens, flowing water speeds the thaw.

  2. Find the cold section.

    Follow the pipe back from the faucet. Likely spots: runs along exterior walls, crawl spaces, unheated garages, the cabinet under a sink on an outside wall, and where the water line comes through the foundation. A frozen section often feels colder than the rest of the pipe or has frost on it.

  3. Apply gentle heat.

    Use a hair dryer, an electric heating pad wrapped around the pipe, towels soaked in hot water, or a space heater kept well away from anything that can burn. Work from the faucet end back toward the ice so the melt water has somewhere to go.

  4. Keep going until full pressure returns.

    Then check every other faucet in the house. If one pipe froze, others in similar spots may have too.

  5. Watch for leaks as it thaws.

    A split pipe often does not leak until the ice melts. Stay nearby with a flashlight and know where your main shutoff is.

Never thaw a pipe with an open flame. No blowtorch, propane or kerosene heater, or charcoal stove. Flames start fires inside walls and can overheat a pipe until it fails. Keep electric heaters and hair dryers away from standing water.

Why frozen pipes burst where there is no ice Water flows from the main toward a closed faucet. An ice plug forms in a cold section along an exterior wall. As more water freezes, pressure builds in the trapped section between the ice and the closed faucet, and the pipe splits there. An open, dripping faucet relieves that pressure. Cold exterior wall From the main Ice plug Pressure builds here Closed faucet Pipe often splits in this section Keep a faucet open or dripping: the pressure has somewhere to go.
Plate 1The ice is not usually what splits the pipe. Pressure trapped between the ice plug and a closed faucet is, which is why an open faucet protects the pipe.

If a pipe has burst

  1. Shut off the main water valve. It is usually where the water line enters the house: in the basement, a utility closet, a crawl space or near the water heater. Turn it clockwise until it stops.
  2. Turn off the water heater if the house will be without water for a while. Follow the label: gas models go to Pilot or Off, electric models are switched off at the breaker.
  3. Open faucets to drain the remaining water and relieve pressure.
  4. Cut power to wet areas at the breaker if water is near outlets, cords or appliances, and only if you can reach the panel without standing in water.
  5. Call a plumber, then your insurer. Photograph the damage before you clean up.

Which pipes freeze first

Location Why it freezes Best protection
Outdoor hose bibs and sprinkler lines Fully exposed to outside air Drain them, close the indoor shutoff, leave the outside tap open
Crawl spaces and unheated basements Cold air, often drafts through vents Pipe insulation; temporarily cover crawl space vents
Attics Little or no heat, often poorly sealed Insulate pipes and the attic floor around them
Garages Doors open to winter air Keep garage doors closed; insulate the lines
Sink cabinets on exterior walls Cabinet doors block warm room air Open the cabinet doors in cold snaps
Pipes along uninsulated exterior walls Wall cavities can be nearly as cold as outside Seal air leaks; consider rerouting the pipe

How to keep pipes from freezing

Before winter. Drain and store garden hoses. Close the indoor valves that feed outdoor faucets and open the outdoor taps so water left in the line can expand without breaking anything. IBHS notes that homes built before about 2010 often lack frost-proof outdoor faucets. Wrap pipes in unheated spaces with foam pipe insulation, and seal gaps where pipes and wires pass through exterior walls. Heat cable listed by a testing laboratory such as UL is an option for runs that freeze every year.

During a cold snap. Let faucets on vulnerable pipes drip. Open sink cabinets on outside walls (move cleaners out of children’s reach first). Keep the garage door shut. Hold the thermostat at the same setting day and night: a slightly higher heating bill costs less than a burst pipe.

When you travel. Leave the heat on at 55°F or higher. If you will be gone for more than a week with hard freezes forecast, IBHS suggests closing the main water valve and draining the lowest faucets so there is little water left in the pipes to freeze.

Using a space heater near pipes? Keep anything that can burn at least 3 feet away, and turn the heater off when you leave the room or go to bed, as the U.S. Fire Administration advises.

When to call a plumber

  • You cannot find the frozen section, or it is inside a wall or ceiling.
  • Heat has not restored flow after an hour or two of steady warming.
  • A pipe is visibly cracked, bulging or leaking.
  • Several fixtures are frozen at once, which can mean the main line is frozen where it enters the house.
Bottom lineOpen the faucet, find the cold spot, and warm it gently with electric heat or hot towels, never a flame. Watch for leaks as it thaws. Before the next cold night, insulate exposed pipes, open sink cabinets on outside walls and let at-risk faucets drip.

Frequently asked questions

Should I leave faucets dripping when it is freezing outside?

Yes, for faucets served by pipes in cold spots. The American Red Cross and IBHS both recommend letting faucets drip in extreme cold. Moving water is harder to freeze, and an open faucet relieves the pressure that builds between an ice blockage and a closed tap, which is what actually splits pipes.

How long does it take a frozen pipe to thaw?

It depends on how cold the space is, how long the frozen section is and how much of it you can reach. Keep warming until full water pressure returns, then keep the faucet dripping until the weather breaks.

Will frozen pipes thaw on their own?

Eventually, when the air around them warms up, but waiting is risky. As the pipe thaws, a hidden split can start leaking, sometimes inside a wall. Thawing it deliberately, with the faucet open and someone watching, lets you catch a leak right away.

What temperature should I keep my house at to keep pipes from freezing?

Both the American Red Cross and IBHS say no lower than 55°F, including while you are away. Pipes in unheated spaces can still freeze at that setting, so also open sink cabinets on exterior walls and insulate exposed pipes.

Does homeowners insurance cover burst pipes?

Many policies cover sudden water damage from a burst pipe but can exclude damage caused by neglect, such as leaving a home unheated in winter. Check your policy and photograph the damage before cleanup.

Sources

  1. Frozen Pipes American Red Cross
  2. Winter Ready: How to Protect Your Home From Winter Weather (checklist) Insurance Institute for Business & Home Safety (IBHS)
  3. Heating Fire Safety U.S. Fire Administration (FEMA)

First published October 7, 2026. Last reviewed October 7, 2026. Spot an error? Tell us and we will check it against the source.

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