How do you safely thaw a frozen pipe?

Open the affected faucet, then apply gentle heat to the frozen section starting at the faucet end and working back toward the coldest spot — never in the middle. Use a hair dryer, a heat lamp, a space heater kept clear of anything flammable, an electric heating pad wrapped around the pipe, or towels soaked in hot water. Never use a blow torch or any open flame: it can scald you, start a fire in the wall, and the sudden heat can crack the pipe. Warm slowly and steadily until full flow returns.

Why should you open the faucet before thawing a pipe?

Opening the faucet does two things. It relieves pressure in the pipe, which lowers the chance of a burst as the ice thaws and expands, and it gives the melting water somewhere to go so you can see your progress — flow returning at the faucet tells you the ice is clearing. Open both the hot and cold handles on the affected fixture. As you warm the pipe from the faucet end back toward the ice blockage, the trickle will grow to a full stream when the pipe is clear.

Where do pipes usually freeze?

In the coldest, least-insulated runs: pipes in exterior walls, unheated basements and crawl spaces, attics, garages, and under sinks on outside walls. Outdoor hose bibs and their supply lines are common victims. The spot that freezes is usually where the pipe passes through or near cold outside air with little insulation. If one faucet has no flow in a cold snap while others work, the frozen section is in the line feeding that fixture — trace it back to the coldest, most exposed run.

How do you know if a frozen pipe has burst?

Watch for these signs once it thaws or while you work: water pooling, dripping, or staining on walls, ceilings or floors; a hissing or rushing sound behind a wall; a sudden drop in water pressure; or a bulge, split or frost-heaved section visible on an exposed pipe. If you shut the water off and a pipe was cracked by the ice, you may not see the leak until it thaws — so if you suspect a burst, keep the main shut off and inspect before restoring full pressure. A burst pipe needs immediate repair.

When should you call a plumber for frozen pipes?

Call a plumber if you cannot locate the frozen section, if it is inside a wall or otherwise inaccessible, if the pipe has already burst or you see any leak, or if the pipe does not thaw with reasonable, safe heat. Also call if you are not confident finding and using your main shut-off in an emergency. A frozen pipe that has cracked will flood the moment it thaws, so a suspected burst is a stop-and-call situation. Repairing burst pipe inside a finished wall is plumber work.

How to Thaw Frozen Pipes Safely (and Prevent a Burst)

Written & researched by Priya Anand DIY & Tools Editor

Updated August 2026

Low-angle view of a person's hands tightening a fitting under a kitchen sink with a wrench, in soft overcast light

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Thawing a frozen pipe is a DIY task if you can reach the frozen section — the key rules are to open the faucet, warm the pipe slowly from the faucet end back toward the ice, and never use an open flame. A hair dryer, heat lamp, space heater, heating pad or hot towels all work. Before anything, find your main water shut-off, because if the ice has already cracked the pipe it will flood when it thaws. Call a plumber if the frozen run is inside a wall, if the pipe has burst, or if you cannot locate it.

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Step 1: Find your main shut-off first

Before applying any heat, locate the main water shut-off for the house — usually where the supply enters, in a basement, crawl space, utility closet, or garage. A pipe cracked by ice will not leak while frozen; it floods the instant it thaws. Knowing where to shut the water off in seconds is your safety net. Keep a bucket and towels handy.

Three-quarter view of a person's hands tightening a fitting under a kitchen sink with a wrench, in soft early-morning light

Tools and materials

A hair dryer, heat lamp, portable space heater (kept clear of flammables), or an electric heating pad.
Towels for hot-water wraps, and a bucket.
Never a blow torch or any open flame.
Pipe insulation and heat tape for prevention afterward. Reference: best plumbing tools.

Step 2: Locate the frozen section and open the faucet

Find the fixture with no flow, then trace its supply line back to the coldest, least-insulated run — an exterior wall, crawl space, or under-sink line on an outside wall. Frost or a visible bulge marks the spot. Open both the hot and cold handles on the affected faucet to relieve pressure and give melting water an exit; the returning trickle will show your progress.

Golden-hour view of a person's hands tightening a fitting under a kitchen sink with a wrench

Step 3: Apply gentle heat from the faucet end back

Start warming the pipe at the faucet end and work back toward the frozen blockage — never start in the middle, which can trap expanding steam between two ice plugs and burst the pipe. Move a hair dryer back and forth along the pipe, wrap it in hot-water-soaked towels, position a heat lamp or space heater a safe distance away, or wrap an electric heating pad around it. Keep any heater well clear of anything flammable and never leave it unattended.

Step 4: Watch for full flow

As the ice melts, the trickle at the faucet grows to a steady stream. Keep applying heat until full flow returns to both hot and cold. Then check the thawed section and everything downstream carefully for any leak or drip — the ice may have cracked the pipe, and the damage shows only once water moves through it again.

Over-the-shoulder view of a person's hands tightening a fitting under a kitchen sink with a wrench, in soft early-morning light

Step 5: Prevent the next freeze

Once thawed, protect the vulnerable run: wrap it with foam pipe insulation or apply UL-listed heat tape, seal drafts near the pipe, and in a hard freeze let a faucet on an exposed line drip overnight and open cabinet doors to let warm air reach under-sink pipes. Before winter, shut off and drain outdoor hose bibs.

Common mistakes

Using a blow torch or open flame, a fire and injury hazard that can crack the pipe.
Heating from the middle of the frozen run, trapping pressure and risking a burst.
Not opening the faucet first, so pressure has nowhere to escape.
Not knowing where the main shut-off is if the pipe turns out to be cracked.

When to call a plumber

Call a plumber if the frozen section is inside a wall or otherwise unreachable, if the pipe has already burst or you see any leak once it thaws, if it will not thaw with safe heat, or if you are not confident locating and using your main shut-off. A suspected burst is a stop-and-call situation: keep the main off and have it inspected before restoring pressure. Repairs inside finished walls are plumber work and are not permit-exempt in every area.

Related: at what temperature pipes freeze, how long a pipe can stay frozen before it bursts, and how to replace a water shut-off valve.

How to Thaw Frozen Pipes