Why Do Frozen Pipes Burst?

Built up pressure between the frozen water and closed off taps can result in a watery mess in your home. (Photo: Paul Tessier/Shutterstock).

Below freezing weather across the country has brought with it a myriad of problems. Most exciting to me as a former teacher? School closings in many towns because the weather was just too cold for kids to be waiting outside a bus stop.

Another issue with below freezing temps? Frozen — and often burst — pipes in our homes. It’s not a fun problem to deal with but it’s helpful to know why pipes are more likely to burst in this kind of weather, and what you can do to prevent it. Most people don’t even think about these kinds of problems until it’s too late, so if you haven’t dealt with burst pipes up till now, sit up and pay attention. If you have, then you might happen know these little nuggets of wisdom all too well.

Strange Timing

First off, it’s important to note that pipes don’t always burst once they’ve been frozen. It’s the thawing of the pipes that can be your biggest problem. It would seem that pipes burst when the temperature goes below freezing because water expands as it freezes. Though this is the case, it is actually once the water inside the pipe starts to melt and rush through the pipe, or the water that is left in the pipe is pushed to a closed faucet by the expanding ice, that the pipe can burst.

Preparing for a Freeze

First off, if you know a freeze is coming, open the kitchen and bathroom cabinet doors to allow the warmer indoor air to circulate around the pipes, keeping them above freezing. Also, it will help to raise the temperature in your house a few degrees. Even though this may cost you a bit more on your heating bill, it can be well worth it if it prevents your pipes from freezing and bursting, leaving you with an unexpected plumbing bill to deal with instead.

If you know the temperatures are going to be really cold one night, you can let the faucets trickle just a drop through the night. Though the noise might wake you up and make you feel the need to use the bathroom – this will actually help prevent the pipes from freezing since water will be constantly moving through them.

How To Warm Them Up, Slowly

What to do if your pipes are already frozen, but haven’t burst?

Try thawing them out slowly. One way recommended by plumbers is to wrap a towel around the pipe (work your way from the pipes opening back, since thawing the water in the middle of the pipe when the ends are still frozen could cause it to burst) and pour hot water over the towel. The towel works to concentrate the warmth around the pipe. Make sure if there’s no sink beneath it, to place a bucket underneath the pipe to catch the excess water. This process can be slow but is effective. You can also shut off the main water valve to your house, stopping any further water from coming into the pipes.

If you don’t want to tackle the problem yourself, or your pipes have already burst, best to call an experienced plumber to resolve the issue. Then, while he’s there, make sure he looks at the rest of the pipes in your house to see if any of them are frozen as well or if there any potential issues he foresees could be a problem. Insulating pipes well within walls can be a costly endeavor, but it can go a long way towards keeping your pipes warm enough to withstand a freeze.