How to Thaw Frozen Pipes Safely: 6 Steps and What to Avoid

How to thaw frozen pipes: open the nearest faucet, then warm the frozen section gently with a hair dryer, heating pad or warm towels, working from the faucet back. Never use a torch or open flame. If you cannot find the frozen part, or see a leak, shut off the water and call a plumber.

How to thaw frozen pipes: the quick answer

Frozen pipes block flow and put pressure on the pipe, which can split it. Thaw slowly with moderate heat and keep the faucet open so melting water and pressure can escape. Start at the faucet end and move toward the frozen section, and check for leaks as the ice melts.

Quick facts: how to thaw frozen pipes
Time needed	30 minutes to a few hours
Tools	Hair dryer, heating pad, warm towels, space heater used safely
Difficulty	Easy if the pipe is reachable
Never use	A propane torch, blowtorch or open flame

First, confirm the pipe is frozen

1. Turn on several faucets. If only a trickle or nothing comes out, a pipe may be frozen.
2. Check whether hot, cold or both are affected. One line points to a single frozen pipe.
3. Look for frost on exposed pipes, or a pipe that feels very cold or has a bulge.
4. Check outdoor walls, crawl spaces, garages, attics and under sinks on exterior walls.

Steps to thaw a frozen pipe

1. Open the faucet on the affected line, so water and pressure can escape.
2. Shut off the main water if you see a split pipe or active leak.
3. Apply gentle heat to the frozen section. A hair dryer on a low setting, a heating pad wrapped around the pipe, or towels soaked in warm water all work.
4. Work from the faucet end toward the frozen section so melted water has an escape path.
5. Keep heating until full flow returns, then run water for several minutes.
6. Check the whole pipe for leaks, since ice can hide a split that only shows when it melts.

What not to do

• Do not use a torch or open flame. It is a serious fire risk and can damage the pipe.
• Do not use a high-wattage heater unattended or point heaters at flammable material.
• Do not use boiling water on exposed pipes in a way that could cause burns or crack a fitting.
• Do not leave the water on if you find a burst.

When the frozen section is behind a wall

If the pipe is inside a wall, ceiling or floor, you can raise the temperature in the room, open cabinet doors, and aim a hair dryer through an access panel. If it will not thaw, or you cannot reach it, call a plumber. They have safe equipment to thaw pipes and repair splits.

Special cases: copper, plastic and pipes in the garage

Copper pipe tolerates gentle heat well. Plastic pipe such as PEX and PVC can be damaged by too much heat, so keep the hair dryer at a distance and move it constantly. Pipes in an unheated garage or crawl space may be thawed by warming the space with a safe, thermostat-controlled heater placed away from anything flammable. Never leave any heat source running unattended.

After it thaws

Look for drips, wet insulation or stains. A pipe that froze once may have a hairline split that leaks later. Insulate that run, and consider heat tape rated for pipes. Mark the spot where it froze so you can protect it before the next cold snap, and ask a plumber about rerouting a pipe that freezes every winter.

Preventing the next freeze

Keep the heat on and set at a safe minimum, open cabinet doors on exterior walls, let a faucet drip during a hard freeze, insulate pipes in unheated spaces, and disconnect outdoor hoses. Knowing how to thaw frozen pipes is useful, but prevention is quicker and cheaper.

Related reading

• Does frozen pipe always burst: What to Do First
• How to prevent burst pipe: A Step-by-Step Guide
• Complete Guide: What to Do When a Pipe Bursts in Your House
• Outdoor Faucet Leaking? Find the Leak, Fix It, Winterize

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