How to Thaw Frozen Pipes

Restore the flow of water and prevent permanent damage to your pipes.

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Photo: Werner Straube

The pipes that flow throughout a house, condo, or apartment building carry hot and cold water to the various sinks, showers, tubs, and appliances. However, when cold weather hits, pipes that are exposed to temperatures below 32 degrees Fahrenheit can begin to freeze. When this happens, a block of ice begins to form in the water line. This can reduce the water pressure or even create a watertight seal that prevents water from flowing to the faucet.

Additionally, when the water freezes, it expands. This expansion can damage pipes, causing leaks or even flooding. Use this guide to learn how to thaw frozen pipes in order to prevent lasting damage to your pipes and restore the flow of water throughout your home.

How to Identify Frozen Pipes

There are several signs that might indicate you have a frozen water pipe, including a reduction in water pressure, leaks, and no water coming from the faucets. If you suspect that one of your pipes is frozen, you need to find the specific pipe before you can attempt to unfreeze it. Turn the faucets on to find out if the issue is affecting the entire home or if it is isolated to a specific area of the home.

When the main water line in the home freezes, water pressure is reduced or the flow of water is completely stopped throughout the entire home. If only one or two faucets and plumbing fixtures are affected, you will have to trace the pipe back from the faucet to find the frozen part of the pipe. Parts of the pipe that are not insulated or that run along an exterior wall are prone to freezing due to exposure to colder temperatures. Look for ice or frost forming on the outside of the pipes to help identify the exact area that is frozen. 

How to Thaw Frozen Pipes

Once you have located the frozen pipe, you'll need to thaw it out gradually over about 30 to 60 minutes. Do not use an open flame to thaw pipes. The flame can cause damage to the surrounding material and pose a risk to the entire home. Additionally, plastic water lines will melt when exposed to fire. Instead, follow these steps to learn how to thaw frozen pipes.

What You Need

  • Drywall knife
  • Reciprocating saw
  • Hair dryer
  • Heat tape
  • Space heater
  • Towel
  • Fan
  • Dehumidifier
  • Shop vac
  • Mop
  • Pipe insulation

Step 1: Turn On Faucet

Head to the nearest affected faucet and turn it on. Even a small amount of water actively running through the faucet should be enough to prevent the pipe from freezing completely. If the water line is already completely frozen, opening the faucet helps to relieve the pressure in the system to reduce the chance that the pipe will burst.

Step 2: Expose the Pipe

In some cases, the frozen pipe is buried in the wall, ceiling, or even the floor. Before you can thaw out the pipe, you will need to gain access by cutting a hole in the drywall or ceiling. Not only will this allow you to apply heat directly to the pipe, but it is also necessary to identify why the pipe is freezing. Water lines tend to be prone to freezing if they are not wrapped in insulation or if they are installed in an especially cold area of the home, like an unheated basement, cellar, or crawlspace. Once the pipe is exposed, you can take steps to thaw it out, then use preventative measures, like insulation or heat tape, to avoid this issue in the future. 

Step 3: Apply Heat

In order to thaw a pipe without damaging it, you will need to gradually apply heat to the affected area. There are several methods you can try, including a hair dryer, heat tape, or a space heater. You can also attempt to thaw out the pipe by simply turning up the heat in the home, but this will take much longer than one of the previously mentioned methods.

If you choose to use heat tape, wrap the tape around the affected area of the pipe, then plug it in to begin heating the pipe. A hair dryer or space heater will need to be directed at the pipe so that the warm air hits the frozen part of the pipe. Be prepared to wait at least 30 to 60 minutes. When the pipe begins to thaw, water will start flowing at a faster rate through the open faucet. Even after the water pressure is fully restored, it’s recommended to keep the heat on the pipe to ensure the ice in the line is completely melted.

Step 4: Check for Leaks

When water in a pipe freezes, it expands and can damage the pipe. A burst pipe is immediately noticeable because water will be flooding into your home, but a smaller leak might go unnoticed if you don’t take the time to look for it. Keep in mind that the pipes may already be wet due to ice forming on the exterior of the pipe. After thawing the water line, use a rag, cloth, or paper towel to wipe the pipe down and inspect it for signs of damage or leaks. 

Step 5: Call a Plumber

If you find that the pipes have been damaged, turn off the water at the main shut-off valve for the home, then contact a plumber to repair the leak or replace a burst pipe. Use towels, a mop, or a wet/dry vacuum to clean up any water as soon as possible to prevent water damage and the formation of mold and mildew. A dehumidifier and fans can also be set up in the area to help absorb the water and dry any affected surfaces. Depending on the severity of the flood, you may need to dispose of water-damaged items and furniture. 

How to Prevent Pipes from Freezing

There are simple, affordable steps you can take to prevent pipes from freezing in the future. Start by identifying any problems in the area where the pipe is installed. For instance, if the outer wall or basement doesn’t have insulation, it’s a good idea to purchase and install insulation. Similarly, if the area is unheated, you can set up a space heater to ensure the water pipe is kept at optimal temperatures throughout the winter months.

Adding pipe insulation to your water lines is another great way to protect a pipe from freezing in the winter and from forming condensation in the summer. You can also wrap the pipe with heat tape. This product heats the pipe with a wire that runs through the tape. Keep in mind that you will need to plug the tape in before it will provide heat. 

Additionally, if you are away from your home for long periods of time, like those that prefer to winter in warmer areas, it’s recommended to keep your home at a higher temperature during the winter months and have someone in the area periodically check to make sure there aren’t any problems.  

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