How to Unthaw a Frozen Pipe

A Frozen Water Pipe Can Cause Severe and Costly Damage to a Home

By Mark J. Donovan

One of the biggest fears for homeowners who live in cold climates is frozen water pipes, or more specifically, frozen plumbing supply lines. A frozen water pipe can burst and cause water to spray from it and damage a home in very short order. Often, however, a frozen pipe may burst and no water escapes from it at first. It’s often after the ambient air temperature warms up that the frozen pipe begins to melt and the water begins to seep or spray from it, inflicting its wrath on the home.

How to detect if you have a Frozen Pipe

If you flush a toilet and the toilet doesn’t refill, or turn on a faucet and no water comes out of it, and the outside air temperature is very cold, there is a very likely chance you have a frozen pipe.

Also, if you have a forced hot water heating system or a hot water to air heat exchanger system, and you don’t feel heat coming from the heating elements or duct registers, then it is also very likely you have a frozen water pipe somewhere in your home.

How to Determine Where the Pipe is Frozen

Trace back from where the problem is observed to determine where the plumbing supply line is frozen. Start at the faucet, for example, and work your way back to the source of the plumbing water supply. Inspect the supply line looking for cracks, leaks or bulges in the supply pipe. Also, inspect the pipe for frost on it. Also feel the pipe. A frozen pipe is very cold, so simply running your hand along the length of the pipe can often identify where the frozen section of pipe is.

Frozen copper pipe

How to Unthaw a Frozen Pipe

First, turn off the main water supply to the house. Then open all the water valves, e.g. sink and tub faucets, in the home to drain as much water out of the system as possible.

Next, with a bucket, towels and mop handy, heat the frozen pipe. Try heating the pipe with a hair dryer, heat lamp or heating pad. You can also wrap hot towels around the affected area of the pipe. When heating the pipe, heat the pipe starting from the side closest to the faucet.

After you think you’ve melted the frozen section of pipe, partially turn the water main valve back on and observe the frozen pipe area. If there are no leaks you’ve dogged a major bullet. If you are unfortunate enough to see a leak, shut off the water main valve and call a plumber immediately.

How to Prevent a Frozen Pipe

To prevent the pipe from freezing in the future, insulate the pipe. Also, you can alternatively wrap the pipe with heating tape.

Frozen pipes are often found in attics, outside walls, basements and crawl spaces. So make sure all water pipes in these areas are properly insulated with pipe foam insulation.

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