How to prevent frozen pipes (and what to do if they freeze)

Quick answer: Keep your heat on — at least 55°F even when you are away — let cold water drip from faucets on exposed pipes during hard freezes, open cabinet doors under sinks on outside walls, insulate pipes in unheated spaces, and disconnect garden hoses. If a pipe freezes, keep the faucet open and warm the pipe gently with a hair dryer or heating pad — never an open flame.

Key takeaways

• Pipes are at risk when outdoor temperatures drop to about 20°F or lower, especially pipes on outside walls or in unheated spaces.
• Keep the house at 55°F or higher, even when you're away.
• A slow drip of cold water keeps pressure from building up in a freezing pipe.
• Know where your main water shut-off is before winter.
• Never thaw pipes with an open flame.

A frozen pipe is not just an inconvenience. Water expands as it freezes, pressure builds between the ice and the closed faucet, and the pipe can split — often releasing hundreds of gallons when it thaws. A few minutes of prevention before the first hard freeze is far cheaper than water damage repairs.

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#Which pipes are most at risk

• Pipes in unheated spaces: crawl spaces, attics, garages, unfinished basements
• Pipes along exterior walls, especially under kitchen and bathroom sinks
• Outdoor hose bibs, sprinkler lines and pool supply lines
• Pipes where the water line enters the house through the foundation

#Before winter: one-time prep

1. Drain and store garden hoses. Close the indoor shut-off valve that feeds each outdoor faucet, then open the outdoor faucet so any water left inside can drain and has room to expand.
2. Insulate exposed pipes. Foam pipe sleeves from a hardware store are cheap and easy. For pipes that freeze often, use UL-listed heat tape or heat cable and follow the instructions exactly.
3. Seal air leaks near pipes — gaps around dryer vents, cable holes and sill plates let cold air blow straight onto plumbing.
4. Find your main water shut-off and make sure it turns. If a pipe bursts, this is the first thing you need, fast.
5. Drain sprinkler and pool lines according to the manufacturer's directions.

#During a cold snap

• Let faucets drip. A slow drip of cold water from faucets served by exposed pipes keeps water moving and relieves pressure if ice starts to form.
• Open cabinet doors under sinks on outside walls so warm room air reaches the pipes. Move cleaning products out of children's reach.
• Keep the garage door closed if water lines run through the garage.
• Keep the thermostat steady day and night. This is the one time to skip a deep nighttime setback.
• Heading away? Leave the heat on, set no lower than 55°F, and ask someone to check the house. For long trips in very cold areas, consider shutting off the main water and draining the lines.

#Signs a pipe is frozen

• You turn on a faucet and get only a trickle or nothing at all
• Frost on an exposed pipe
• A bulge or crack in the pipe
• An odd smell from a drain (sewer gas backing up)

#How to thaw a frozen pipe safely

1. Open the faucet the pipe feeds. As the ice melts, running water helps melt the rest and relieves pressure.
2. Find the frozen section. Start near the faucet and work back: exterior walls and where the line enters the house are common culprits.
3. Apply gentle heat: an electric hair dryer, an electric heating pad wrapped around the pipe, a portable space heater kept well away from anything flammable, or towels soaked in hot water.
4. Never use an open flame — no blowtorch, propane or kerosene heater, or charcoal stove. It is a fire hazard and can damage the pipe.
5. Do not use electrical devices near standing water.
6. Keep heating until full water pressure returns, then check every other faucet in the house — if one pipe froze, others may have too.

Call a licensed plumber if you cannot find or reach the frozen section, the pipe will not thaw, or you see any crack.

#If a pipe bursts

1. Shut off the main water valve immediately.
2. Turn off electricity to the affected area if water is near outlets or appliances — only if you can reach the panel safely.
3. Open faucets to drain the remaining water.
4. Call a plumber, then photograph the damage for your insurer.
5. Start drying right away: mop up, run fans and a dehumidifier, and remove wet rugs. Mold can begin to grow within a day or two.

#Long-term fixes for pipes that freeze every year

• Have a plumber reroute problem pipes away from exterior walls or into heated space.
• Add insulation to the crawl space, rim joists or attic.
• Install frost-free outdoor faucets, which shut off the water inside the warm part of the wall.
• Add a smart leak detector or automatic water shut-off valve; many can alert your phone. See our Matter smart home guide.

#Going away in winter? Checklist

• ☐ Set the thermostat to at least 55°F
• ☐ Open cabinet doors under sinks on outside walls
• ☐ Ask someone to check the house daily during a cold snap
• ☐ Consider shutting off the main water and draining the lines for long trips (and turn off the water heater per its manual)
• ☐ Install a smart leak detector or automatic shut-off valve
• ☐ Disconnect garden hoses and close the indoor valve to outdoor faucets

#Smart leak detection and auto shut-off

Some insurers offer discounts for leak detection or auto shut-off devices — ask yours.

#Renters: what you should do

• Tell your landlord right away about drafts, broken windows or no heat.
• Keep the heat on and cabinet doors open during cold snaps.
• Know where the shut-off valve is — ask the landlord.
• Renters insurance usually covers your belongings if a pipe bursts, but not the building.

#Does insurance cover burst pipes?

Standard homeowners policies usually cover sudden and accidental water damage from a burst pipe. But claims can be denied if the home was left unheated or the damage built up slowly. Keep the heat on, document your precautions, and report damage quickly. See mold removal cost if water damage isn't dried fast.

#Frequently asked questions

At what temperature do pipes freeze?

Water freezes at 32°F, but pipes inside a home usually freeze when the outdoor temperature drops into the low 20s or below for several hours, especially when the pipes are in unheated spaces or exterior walls. Wind makes it worse.

Should I let all my faucets drip?

Only those fed by pipes in exterior walls or unheated spaces. A slow, steady drip of cold water is enough.

What temperature should I keep my house to prevent frozen pipes?

The American Red Cross recommends keeping the heat set no lower than 55°F if you will be away during cold weather.

Will frozen pipes thaw on their own?

They may as the weather warms, but a pipe can split while frozen and only leak once it thaws. It is safer to thaw it deliberately with the faucet open, so you notice a leak right away.

Can PEX pipes freeze?

Yes. PEX is more flexible than copper and less likely to burst, but water inside can still freeze and fittings can fail.

How long does it take for pipes to freeze?

It depends on insulation and wind, but unprotected pipes in unheated spaces can freeze within hours once it's well below freezing.

Does homeowners insurance cover frozen pipes?

Usually, if the damage is sudden and you took reasonable care, like keeping the heat on. Claims may be denied if the house was left unheated.

#Sources

• American Red Cross — How to prevent and thaw frozen pipes
• U.S. Department of Energy — Insulating pipes (Energy Saver)
• Ready.gov — Winter weather
• National Weather Service — Cold weather safety