Frozen Pipes: Prevent Them, Thaw Them Safely and Spot a Burst

Frozen pipes are prevented by keeping heat in the home, insulating pipes in unheated spaces, opening cabinet doors and letting faucets drip during hard freezes. If a faucet gives only a trickle or nothing, keep that faucet open and warm the frozen section gently with a hair dryer, heating pad or warm towels, never an open flame, as the American Red Cross advises. If you cannot find or reach the frozen spot, or it will not thaw, call a licensed plumber.

Why frozen pipes burst

Water expands as it freezes. Researchers at the University of Illinois Sustainable Technology Center explain that it is the water pressure that leads to a pipe's failure: as ice forms along a pipe, pressure in the trapped water soars. That is why a pipe often splits somewhere other than the iciest spot, and why an open, dripping faucet helps by giving that pressure somewhere to go.

Freezing is also a large source of insurance losses. The Insurance Information Institute groups "water damage and freezing" together and reports an average claim of $15,400 for that category over 2019 to 2023, with about one in 60 insured homes filing such a claim each year.

Which pipes freeze first

The Insurance Institute for Business & Home Safety (IBHS) found that burst pipes are the leading cause of damage from extreme cold, especially when power fails for more than 24 hours. IBHS points to these risk factors:

• Location: pipes in crawl spaces, attics, garages and along exterior walls. IBHS notes that plumbing on exterior walls and pier-and-beam construction are common across the South, where hard freezes are less frequent.
• Material: PEX, PVC, copper and galvanized steel can all fail when pressurized and uninsulated in long freezes. IBHS calls uninsulated copper the most problematic. Plastic pipe can become more brittle with age and sun exposure.
• Outages: homes lose heat when the power goes out, and pipes on exterior walls reach dangerous temperatures first.

Other trouble spots include outdoor hose bibs, sprinkler lines, pipes under kitchen and bathroom sinks on outside walls, and supply lines to toilets in cold bathrooms.

How do you prevent frozen pipes?

These steps come from the Red Cross, IBHS and the Insurance Information Institute.

Before winter

1. Insulate exposed pipes. IBHS recommends insulating pipes in attics, crawl spaces and along outside walls, and wrapping pipes and faucets in unheated or minimally heated areas. The Red Cross also mentions UL-listed heat tape or heat cable on exposed pipes.
2. Seal gaps. IBHS advises sealing openings where pipes, vents and wiring pass through exterior walls, and caulking around windows and doors.
3. Shut off and drain outdoor faucets. IBHS says homes built before 2010 typically do not have frost-proof outdoor faucets, so turn off the indoor valve that feeds them or cover them. Drain hoses and irrigation systems.
4. Cover ventilated crawl spaces temporarily during cold snaps, as IBHS suggests.
5. Find your main water shutoff and make sure it turns, so you can close it quickly if a pipe bursts.

During a hard freeze

• Keep the heat steady. The Red Cross advises keeping the thermostat at the same temperature day and night. IBHS recommends keeping it at least 55°F.
• Open cabinet doors under sinks, especially on outside walls, so warm air reaches the pipes.
• Let faucets drip. The Red Cross says running water through the pipe, even at a trickle, helps prevent freezing.
• Keep garage doors closed if water lines run through the garage.

When you travel

The Red Cross says to leave the heat on and set no lower than 55°F if you will be away during cold weather. The Insurance Information Institute suggests asking a neighbor to check the house regularly, or having a professional drain the water system for longer absences. Check your policy too: the Insurance Information Institute notes most homeowners policies have a vacancy clause that limits or excludes coverage when a home is unoccupied for typically 30 to 60 consecutive days.

Signs your pipes are frozen

• Little or no water from a faucet. The Red Cross says to suspect a frozen pipe if only a trickle comes out.
• Frost on a visible pipe, or a pipe that feels extremely cold.
• A toilet that will not refill, pointing to a frozen supply line.
• Odd smells or slow drains, which can mean drain pipes are frozen and water has nowhere to go.
• Frozen pipes with no water anywhere in the house can mean the main line or meter area froze.

What to do if your pipes are frozen

1. Check whether anything has burst. Look and listen for water before you add heat. If you see water, shut off the main valve first and go to our burst pipe guide.
2. Open the faucet the frozen pipe feeds. The Red Cross says keeping it open lets water flow as the ice melts.
3. Find the frozen section. Start near the faucet and work back toward the coldest part of the run, such as an exterior wall or crawl space.
4. Apply gentle heat. The Red Cross lists an electric heating pad wrapped around the pipe, a hair dryer, a portable space heater kept away from flammable materials, or towels soaked in hot water.
5. Keep heating until full pressure returns, then check every other faucet in the house for more frozen spots.
6. Watch the thawed pipe for drips or spraying as water flows again. A crack can stay hidden until the ice melts.
7. Call a licensed plumber if you cannot find or reach the frozen area, or the pipe will not thaw.

How to thaw frozen pipes safely

• No open flames. The Red Cross says do not use a blowtorch, kerosene or propane heater, charcoal stove or other open-flame device. These are fire risks, and fuel-burning heaters used indoors can produce carbon monoxide.
• Keep electricity and water apart. A hair dryer for frozen pipes or a space heater should never be used near standing or dripping water. The CDC warns never to use an electric tool or appliance while standing in water.
• Do not leave heaters unattended near walls, insulation or stored items.
• Pipes inside walls you cannot reach are a job for a plumber; raising the home's heat is the safe first step.

If your power is out and you are using a generator, the CDC says never to run it inside a home, basement or garage, or less than 20 feet from any window, door or vent.

PEX, PVC and drain pipes

PEX pipes frozen in a cold run are not automatically safe: IBHS lists PEX among materials that fail when pressurized and uninsulated in long freezes. Frozen PVC pipes can crack, and IBHS notes older plastic can become brittle. Use the same gentle heat for either and never a torch, which can melt or ignite plastic. Frozen drain lines are a separate problem: do not keep running water into a drain that is not flowing, or it can back up.

The term "AC frozen pipes" usually refers to ice on an air conditioner or heat pump refrigerant line, which is a different issue. Turn the system off and call an HVAC technician.

Will a pipe unfreeze on its own?

It can as temperatures rise, but waiting is risky. Pressure can keep building while the pipe stays frozen, and a hidden crack may start leaking the moment the ice melts, possibly while no one is home. The Insurance Information Institute says if pipes are frozen, don't wait for them to burst. If one has already split, our burst pipe water damage page explains what cleanup involves.

Frozen pipes damage and insurance

The Insurance Information Institute says standard homeowners policies cover most of the kinds of damage that result from a freeze, such as pipes that freeze and burst. Coverage can be limited if the home was left without heat or vacant, so read your policy and call your insurer early. Photograph the damage and keep repair receipts. Our water damage insurance claims guide explains the process.

Frozen pipe repair cost depends on where the break is, whether walls or ceilings must be opened to reach it, the pipe material, and how much water escaped before the main was shut off. The water damage, not the pipe, is usually the bigger bill. If a pipe has already burst, see our guide to burst pipe cleanup and repair, and our drying out water damage guide for how to confirm the area is dry. Our signs of water damage guide helps you spot leaks hidden in walls and ceilings after a thaw. To find help by area, visit our locations page.

Flood Rescue Pros is a free service that connects homeowners with independent local water damage restoration companies. If a frozen pipe has already caused water damage and you would like to be connected with one near you, Get help now.

Frequently asked questions

Do you let hot or cold water drip to keep pipes from freezing?

Drip the faucet served by the pipes most at risk. Red Cross guidance mentions letting cold water drip, while the Insurance Information Institute suggests opening both hot and cold taps slightly; either keeps water moving and relieves pressure.

How do I tell if a frozen pipe burst?

Look for water on floors, ceilings or walls, listen for running water with all fixtures off, and watch your water meter. The EPA notes that if your meter reading changes during a two-hour period with no water use, you likely have a leak.

Do I need to turn off the water heater if pipes freeze?

Not usually, if the tank stays full. If you shut off the main water and drain the plumbing, turn the heater off or to pilot too, because manufacturers such as A.O. Smith warn never to run a heater unless it is completely full of water. Our water heater leaks guide covers related problems.

Can I use a hair dryer to thaw frozen pipes?

Yes. The Red Cross lists a hair dryer as a safe heat source. Keep it away from any water, start near the open faucet, and work back along the pipe.

Should I call a plumber for frozen pipes?

Call a plumber if you cannot find or reach the frozen section, it will not thaw, or any pipe has cracked. That is the Red Cross guidance too.

Key facts

• Pipes burst because of water pressure that builds as ice forms, so an open, dripping faucet helps relieve it.
• Highest-risk pipes are in crawl spaces, attics, garages and exterior walls, especially during power outages longer than 24 hours (IBHS).
• Keep the thermostat steady day and night and at least 55°F, including when you are away.
• Thaw with a hair dryer, heating pad, space heater or hot towels; never use an open flame or fuel-burning heater indoors.
• Standard homeowners policies cover most freeze damage, but vacancy clauses can limit coverage (Insurance Information Institute).
• The average water damage and freezing claim was $15,400 over 2019 to 2023 (Insurance Information Institute).