How to Thaw Frozen Pipes Safely | Curb Calc

Faucet down to a trickle? Keep it open and warm the pipe slowly with a hair dryer or hot towels, never an open flame. Plus what to do if a pipe bursts.

11/7/20264 min read

Curb Calc cover titled How to Thaw Frozen Pipes, with a photo of ice hanging from a pipe in a stone wall, a FREE CALCULATOR badge, a note from Portland Water Bureau that frozen pipes can burst as they thaw, and a do and don't table: open the faucet, use hot rags not a torch, warm slowly without boiling, and shut the main if it bursts.Curb Calc cover titled How to Thaw Frozen Pipes, with a photo of ice hanging from a pipe in a stone wall, a FREE CALCULATOR badge, a note from Portland Water Bureau that frozen pipes can burst as they thaw, and a do and don't table: open the faucet, use hot rags not a torch, warm slowly without boiling, and shut the main if it bursts.

You turn on the kitchen tap on a 10°F morning and get a thin trickle, then nothing. The Red Cross says that points to a frozen pipe, and Portland's Water Bureau warns frozen pipes are more likely to burst as they thaw. Find your main shutoff first, then warm the pipe slowly.

Quick answer: keep the faucet open and warm the frozen section with a hair dryer, heating pad or hot, wet towels until full pressure returns. No torch or open flame (Red Cross). Can't find or reach it? Call a licensed plumber.

Free calculator: meltwater pooling by the foundation? Figure gravel in our free French drain calculator.

A column of ice hanging from the mouth of a pipe set in a mossy stone wall
A column of ice hanging from the mouth of a pipe set in a mossy stone wall

Photo: Sergej on Unsplash

Frozen or burst? Check first

Frozen: only a trickle comes out (Red Cross).

Burst: water spraying or pooling. Skip to "If a pipe burst."

Before any heat: find the main shutoff. Portland says most sit where the line enters the house: by the front hose faucet, near the water heater in the basement, or in the garage.

A hand on a chrome kitchen faucet, water splashing out of a glass into the sink
A hand on a chrome kitchen faucet, water splashing out of a glass into the sink

Photo: Jacek Dylag on Unsplash

How to thaw a frozen pipe: 5 steps

1. Open the faucet. Running water helps melt the ice (Red Cross).

2. Find the cold spot. Check exterior walls, where the line enters through the foundation, and unheated crawl spaces, garages and kitchen cabinets (Red Cross).

3. Warm it slowly. A heating pad wrapped on the pipe, a hair dryer, a space heater kept away from anything flammable, or hot, wet towels (Red Cross).

4. Stop at full pressure (Red Cross), then test every faucet. If one pipe froze, others may have too.

5. Wrap it, watch it. Bellevue says swap wet rags for dry insulation, and a broken pipe may leak once thawed.

What never to use

Open flame: no blowtorch, kerosene or propane heater, or charcoal stove (Red Cross).

Boiling heat: DC Water says heat that boils the melted ice can break the pipe.

A space heater left alone: keep anything that can burn at least 3 feet away, and turn it off when you leave the room (U.S. Fire Administration).

Electric at all? Bellevue is stricter: no electric devices (fire and shock risk), just rags with hot water poured over them.

Insulated water pipes running through open wall framing during a renovation
Insulated water pipes running through open wall framing during a renovation

Photo: Olek Buzunov on Unsplash

In a wall or crawl space

Can't find it, reach it or thaw it: call a licensed plumber (Red Cross, DC Water).

Crawl space: one of the likeliest spots to freeze (Red Cross). Use hot, wet rags there (Bellevue); no flame, no space heater.

Frozen meter? Call your water utility (Bellevue).

Two red-handled valves on a dark tiled wall above a black pipe
Two red-handled valves on a dark tiled wall above a black pipe

Photo: Yuriy Vertikov on Unsplash

If a pipe burst

1. Close the main shutoff now (Portland, Bellevue).

2. Turn off the water heater, and find the valve on its cold-water inlet (Portland).

3. No main valve, or broken? Call your water utility's 24-hour line (Portland). Some, like Bellevue, let owners turn the meter valve clockwise with a meter key.

4. Apartment? Call your property manager (Portland).

5. Call a licensed plumber. Portland says repairs past the meter are the owner's job.

A white farmhouse with a front porch and an American flag, snow on the lawn
A white farmhouse with a front porch and an American flag, snow on the lawn

Photo: Brooke Balentine on Unsplash

Keep it from freezing again

From the Red Cross:

Drip: on very cold nights, drip cold water from faucets on exposed pipes.

Doors: open sink cabinets; keep the garage shut if pipes run through it.

Thermostat: same day and night, 55°F or higher if you're away.

Insulate: pipe sleeves or UL-listed heat tape. Compare kits: best heat tape for pipes.

Outside: when to turn off outdoor faucets, and how to blow out a sprinkler system.

A man in a red shirt working on the drain pipes inside a lit sink cabinet
A man in a red shirt working on the drain pipes inside a lit sink cabinet

Photo: Timur Shakerzianov on Unsplash

Frozen pipe FAQ

Can I use a hair dryer to thaw a frozen pipe?

The Red Cross and Portland say yes. Bellevue says no electric devices; hot, wet rags are the cautious pick.

Should I leave faucets dripping?

On very cold nights, for faucets on exposed pipes. DC Water says the cold water is above freezing and helps keep pipes from freezing.

Should I turn off the main if a pipe is frozen?

Know where it is, and close it the moment a pipe leaks or bursts (Portland). Leaving a home unheated? Bellevue says shut the main and water heater, then drain the faucets.

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Sources: American Red Cross, Preventing & Thawing Frozen Pipes; DC Water, Protect Your Pipes from the Cold; Portland Water Bureau, Jan. 2024; City of Bellevue, Prevent Frozen Pipes; U.S. Fire Administration, Heating Fire Safety.