How to Thaw Frozen Pipes Safely Without Bursting Them

To thaw a frozen pipe, open the faucet it feeds, then warm the pipe with a hair dryer on low or medium heat, starting near the faucet and working toward the ice. Keep it moving. Never use a torch or open flame. If the pipe is cracked or leaking, shut off the main water valve and call a plumber.

A faucet that gives only a trickle, or nothing at all, on a cold morning usually means a frozen pipe. The good news is that a frozen pipe is not always a broken pipe. If you thaw it slowly and safely, you may avoid a flood. This guide shows how to find it, thaw it, and what to do if it has already burst.

How do I know a pipe is frozen?

• Water slows to a trickle or stops completely
• Only one fixture is affected, or only the hot or cold side
• Frost or ice on an exposed pipe
• Temperatures have been below freezing and the pipe runs through an unheated area

If no water comes out anywhere, check whether the problem is the whole house or one line. If no tap works, the frozen section may be near the meter or where the main enters the house.

Likely trouble spots are pipes in exterior walls, crawl spaces, attics, garages, basements and under sinks on outside walls.

Before you start

1. Open the faucet. Open the tap the frozen pipe feeds. Water needs an exit as the ice melts, and steam or pressure can build and burst a pipe without one.
2. Look for leaks and cracks. If you see water, a bulge or a split, stop. Shut off the main water valve and call a plumber.
3. Find the main shutoff. Know where it is before you thaw anything.
4. Find the frozen section. Feel along the pipe. A frozen part is colder, may have frost on it, and is often nearest an outside wall.

How to thaw frozen pipes step by step

Method 1: Hair dryer (best for most homes)

1. Keep the faucet open.
2. Plug the dryer into a GFCI outlet and keep it away from standing water.
3. Set it on low or medium heat.
4. Start at the end of the frozen pipe nearest the faucet and work back toward the ice. This lets melted water flow out as you go. Starting at the far end can trap water between the heat and the ice, building pressure.
5. Keep the dryer moving. Do not hold it on one spot or on fittings and joints for long.
6. Keep going until full water pressure returns.

Method 2: Warm towels

Soak towels in hot water, wring them out and wrap them around the pipe. Re-soak and repeat. It is slow, but safe.

Method 3: Heating pad or heat tape

An electric heating pad wrapped around an exposed pipe works well. Heat tape or heat cable made for pipes is safe if you use it as directed. Never wrap heat tape over itself, because it can overheat.

Method 4: A space heater, with care

Set a space heater with tip-over protection a safe distance from the pipe, in a room where it can warm the air near the pipe. Keep it at least three feet from anything flammable and never leave it running unattended. If the heater starts to smell like burning, see space heater smells like burning.

Method 5: Warm the room

If the pipe is behind a wall, open the cabinet doors under sinks on outside walls and turn up the heat so warm air reaches the pipes.

What never to use

Also avoid:

• Boiling water poured on a pipe. It can crack cold pipes.
• A heat gun held in one place.
• Direct heat near gas lines.
• Waiting for a thaw while ignoring a leak.

What if the pipe has burst?

Frozen pipes often crack, but you may not see it until the ice melts and water flows.

1. Shut off the main water valve right away.
2. Open the faucets to drain what is left in the lines.
3. Turn off the electricity to any wet area if water is near outlets or appliances, and only if it is safe to reach the panel.
4. Take photos for your insurer.
5. Call a plumber.
6. Dry the area with towels, fans and a wet vacuum.

If you notice a wet spot or a hissing noise you cannot trace, see hidden moisture problems. If the pipes bang when you turn the water off, that is a different problem. See pipes banging when water is turned off.

What if I cannot find the frozen spot?

• The pipe may be inside a wall, floor or ceiling.
• The freeze may be in the main line outside the house or at the meter.
• Open nearby cabinet doors and raise the thermostat.
• Call a plumber if you cannot reach it. Pros have tools that safely thaw pipes inside walls.

Do not cut into drywall yourself unless you know where the pipe is.

When to call a plumber

• The pipe has burst or leaks
• You cannot find the frozen section
• The pipe is in a wall, under a slab or underground
• There is still no water after an hour of safe thawing
• It happens again and again
• The frozen pipe is next to a gas line

After the pipe thaws

1. Keep the faucet open for a few minutes until it runs normally.
2. Check the pipe for beading, drips or dampness. A bead of water forming on the pipe can mean a small crack.
3. Check the other taps in the house.
4. Turn faucets off and watch for leaks over the next hour.

How to stop pipes from freezing again

• Let faucets drip slowly on very cold nights
• Open cabinet doors so warm air reaches the pipes
• Keep the thermostat at 55°F or higher, even when you are away
• Insulate exposed pipes in basements, crawl spaces and attics
• Seal drafts near pipes. See finding drafts and air leaks
• Disconnect garden hoses and shut off outdoor spigots

See preventing frozen pipes for the full prevention plan. If the power goes out in a cold snap, our blackout checklist has steps to protect your plumbing.

Bottom line

Open the tap, warm the pipe slowly with a hair dryer or warm towels, and work from the faucet toward the ice. Never use a flame. If you see a leak, shut off the main water and call a plumber.