How to Prevent Frozen Pipes — And What to Do If One Bursts

A burst pipe is one of the most destructive things that can happen to a home in winter. Water flows from a burst pipe at 4 to 8 gallons per minute — meaning a single pipe can dump hundreds of gallons into your home in under an hour before anyone notices. The average repair costs around $900 just for the pipe itself, not counting water damage remediation, which can run into the thousands.

The good news: frozen pipes are almost entirely preventable with simple, low-cost steps taken before temperatures drop.

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Why Pipes Freeze and Burst

Water expands when it freezes — by about 9% in volume. In a sealed pipe, that expansion has nowhere to go. The pressure that builds can exceed what most pipe materials can withstand, causing a crack or full rupture. When the ice eventually thaws, water flows freely through the break.

According to the American Red Cross, the pipes most at risk are those in:

• Unheated interior spaces: basements, attics, crawl spaces, garages
• Exterior walls with little insulation
• Cabinets on exterior walls (under kitchen or bathroom sinks)
• Pipes running through unheated garages

Pipes do not typically freeze at 32°F. Most freezing occurs when outdoor temperatures drop to 20°F or below and pipes are in spaces that cannot stay warm enough, per This Old House.

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7 Steps to Prevent Frozen Pipes

1. Disconnect and Drain Outdoor Hoses

Before the first freeze, disconnect all garden hoses from outdoor spigots (hose bibs). Water trapped in a connected hose can back up into the pipe inside the wall and freeze. Per ProtectYourPipes.org, also shut the indoor isolation valve that feeds each outdoor spigot, then open the exterior valve to let any remaining water drain out.

2. Insulate Pipes in Unheated Spaces

Foam pipe insulation is available at hardware stores for a few dollars per length. It is one of the most cost-effective preventive measures you can take. Wrap any pipes in your basement, crawl space, attic, or garage — especially those running along exterior walls. This Old House calls this the single most impactful step for homes in cold climates.

3. Keep the Thermostat at 55°F or Higher — Even When Away

If you leave for a winter vacation, do not turn the heat all the way off. The American Red Cross recommends keeping your thermostat set to no lower than 55°F. The small heating cost is far less than the cost of a burst pipe. Also, keeping the thermostat at a consistent temperature day and night is more protective than letting it drop overnight — temperature swings create stress on pipes.

4. Open Cabinet Doors Under Sinks on Exterior Walls

Cabinets under kitchen and bathroom sinks, particularly those on exterior walls, can get surprisingly cold because warm household air does not circulate into them well. On especially cold nights, open those cabinet doors so warm air can reach the pipes. Per Bob Vila, this simple step can make a meaningful difference for pipes near exterior walls.

5. Let a Faucet Drip During Extreme Cold

When temperatures drop severely (typically below 20°F), let the faucet served by exposed pipes drip slightly — just a trickle of cold water. Moving water is significantly harder to freeze than still water. This is most useful for faucets on exterior walls or in rooms that stay cold. It wastes a small amount of water but can prevent a costly burst.

6. Seal Gaps and Air Leaks Near Pipes

Cold air drafts from gaps in exterior walls, foundation sills, or around utility penetrations can expose nearby pipes to freezing temperatures even inside the home. Caulk or foam-seal any visible gaps where pipes pass through exterior walls or where cold air can infiltrate near pipe runs.

7. Know Where Your Main Shutoff Is

This is not a prevention step — it is emergency preparedness. Know exactly where your home's main water shutoff valve is and make sure it turns easily. If a pipe does burst, getting to that valve in the first minute can prevent tens of thousands of dollars in water damage.

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If You Suspect a Pipe Is Frozen (But Hasn't Burst)

Signs of a frozen pipe: you turn on a faucet and get no water (or just a trickle) on a cold morning.

If the pipe has not burst yet:

1. Open the faucet so water can flow as the pipe thaws.
2. Apply gentle heat to the frozen section — a heating pad, electric hair dryer on low heat, or warm towels. Work from the faucet end toward the frozen section.
3. Never use an open flame — a torch or open flame is a fire hazard and can damage pipes.
4. Call a plumber if you cannot locate the frozen section or if thawing it yourself seems risky.

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What Does Burst Pipe Repair Cost?

Based on data from Angi:

Service	Typical Cost
Burst pipe repair (pipe only)	~$900 average
Labor + materials per linear foot	$150 – $250
Water damage remediation	Varies widely — can be $1,000 to $10,000+

The pipe repair itself is often the smaller part of the total cost. Water damage to drywall, flooring, insulation, and personal belongings can multiply the total significantly. Homeowner's insurance often covers sudden and accidental burst pipes — review your policy before winter.

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When to Call a Licensed Plumber

• If you cannot locate the frozen section of pipe.
• If you thaw a pipe and discover it has already cracked — turn off the main water supply and call immediately.
• If a pipe bursts — shut the main water supply off first, then call.
• If you want a professional assessment of your home's most vulnerable pipe locations before winter.

Find a licensed plumber near you for winterization services or burst pipe repair.

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Key Takeaways

• Pipes most at risk: unheated basements, attics, garages, exterior walls, and under-sink cabinets on exterior walls.
• Most freezing occurs at 20°F or below — prevention is most critical during deep cold snaps.
• Top prevention steps: disconnect outdoor hoses, insulate pipes, keep heat at 55°F+ when away, open cabinet doors under sinks, let faucets drip in extreme cold.
• A burst pipe releases 4 to 8 gallons per minute. Knowing where your main shutoff is can save tens of thousands in water damage.
• Pipe repair averages around $900, but water damage remediation can be far more — review your homeowner's insurance policy before winter.