How to Thaw Frozen PEX Water Lines

PEX water lines are a thermo set material that is cross linked. Despite the fact that PEX piping is made from a high density polyethylene and is popular specifically because of its ability to withstand intense hot or cold. However, in extremely cold temperatures these lines can still freeze up. While this is something that is not common, it is still possible. If your piping is frozen, there is a simple DIY solution to your problems.

Step 1 - Check for Cracks

First, make sure that none of the water lines have cracked. Sometimes, the water will expand whenever it is frozen into ice and the eventual force of the ice expanding in the water line can easily cause it to crack.

If there is a crack, then you will need to repair the entire water pipe, but otherwise continue with the thawing process.

Step 2 - Turn off Water

Once you have checked to make sure that your frozen PEX water line has not in fact split, you are ready to turn off the water that is leading into the line. If you are in an older home, then you will usually have to shut off your main water supply that goes directly into your home.

However, if you happen to have a new home, then you will be able to find intermediate water shut off valves that may be installed. This will allow you to simply isolate the frozen water line that you are going to have to work on.

Step 3 - Open Faucets

Once the water has been turned off, you will need to open up any faucets that the frozen water line connects to. This will allow you to completely get rid of the cold water that is inside of your pipe and lowers pressure so that the water can flow out of your pipe easily, once it’s been completely thawed.

Step 4 - Thaw

You are now ready to thaw your water lines. There are a couple of different ways that you can go about doing this. It will depend on what you already have available as well as how hard it will be to get to your PEX water line that is frozen.

The PEX piping that froze up can be heated using either a blow dryer to create a point of heat for the ice and water to travel through. Alternatively, you can wrap the PEX line with cloths or bath towels and pour out hot water from your kettle over the towels.

If you can’t access many parts of the piping, just focus repeatedly on the lengths you can interact with. Heating those small spots considerably and consistently should eventually promote the thawing of the ice.

Thaw Frozen PEX Water Lines FAQ

How do you thaw a frozen PEX water line in the wall?

When a water line has frozen water inside of it and the pipe is inside of a wall, you will notice issues with sluggish water or perhaps no water coming out of faucets. Unthawing a frozen pipe inside a wall is difficult but not impossible.

Turn the heat up in the house. Make the temperature warmer and the pipes should unthaw on their own.

If temperatures are very cold outside and turning the heat up in the home does not seem to be effective, try pointing a space heater or heat lamp directly at the wall where the pipe is located. This will focus and direct more heat right where it's needed.

If even this does not work, you will need to cut into the drywall to expose the pipes so they can receive heat more directly.

How long does it take for PEX pipes to thaw?

There are several different methods for unthawing PEX pipes when they freeze, so unthawing times tend to vary slightly between methods. On average, it will take about 30 minutes for the pipes to fully unthaw no matter which method you use to unfreeze the ice.

Will PEX water line break if it freezes?

PEX is a highly flexible material and it is often touted as freeze-proof. However, nothing is freeze-proof.

In cold enough conditions, all water will freeze. This is its nature and even well-insulated and protected pipes can freeze in extremely cold conditions.

PEX can freeze and burst, resulting in damage to the pipe, when temperatures reach 20 degrees F. Insulated pipes can withstand colder temperatures by a few degrees.

If there is enough water in the line that freezes inside the pipe and stretches the PEX beyond its limit, the pipe can rupture and break.

Can you thaw PEX with a heat gun?

A natural source of heat is flame, and there are several tools that can create flame to provide quick heat. However, you shouldn't use anything that creates a flame, such as a torch or a heat gun, to unthaw your pipes.

Too much heat can do damage to pipes, the same way that too much cold can damage pipes. You may want to find the quickest method to unthaw frozen pipes but quicker is not better.

Use less harsh methods to heat up pipes and they will unthaw, not immediately but safely.

Will running hot water unfreeze pipes?

Hot water can help to thaw out pipes that have frozen, if you've identified which faucet the pipe is connected to. Try running hot water for about 20 minutes and see if this has an effect on helping the ice to melt.