Frozen pipes: what to do right now

How to thaw a frozen pipe safely

1. Open the faucet the frozen pipe feeds, both hot and cold sides. This relieves pressure and lets you see when flow returns.
2. Apply gentle heat to the frozen length: a hair dryer, a heating pad, hot-water-soaked towels, or a portable space heater kept clear of anything flammable.
3. Work from the faucet end toward the coldest spot, so melted water can drain out ahead of the ice.
4. Never use a blowtorch, a propane heater, or any open flame on a pipe. It can damage the pipe and start a fire.
5. If you cannot find or reach the freeze, or a pipe has already burst, shut off the main water valve and call a licensed plumber.

Thawing guidance: This Old House, dealing with frozen pipes.

Why a burst is the real danger

Water expands as it freezes, and in a closed pipe that expansion builds pressure until something gives. That is why the fix and the prevention both center on keeping water moving and giving pressure somewhere to escape. A burst pipe is not just a plumbing repair; the water damage that follows is often the larger bill.

How to keep pipes from freezing

• Let a faucet drip. On the coldest nights, let the faucet farthest from your water main drip slowly, both hot and cold. Moving water is much harder to freeze.
• Keep the heat at 55°F or higher. Even when you are away, and do not drop it at night during a freeze.
• Open cabinet doors. Under sinks on exterior walls, open the cabinet so warm household air reaches the pipes.
• Insulate exposed pipes. Foam sleeves in attics, basements, and crawl spaces, with extra attention to elbows and joints, and seal cracks where utility lines enter the house.

Prevention guidance: This Old House, how to prevent frozen pipes.

If a pipe does burst, our note on what a burst or frozen-pipe repair tends to cost is folded into the same winter planning: the thaw itself is usually modest, but replacing a split section and drying out the damage is where the cost lives.