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What to do if your pipes freeze (or worse, burst!)

Outdoor faucet frozen in the winter

It’s every homeowner’s nightmare: a frozen pipe that could burst and flood your basement. Fortunately, there are ways to prevent frozen pipes. There are also important steps you can take in the event of a frozen pipe to minimize the risk of damage to your home.

What causes frozen pipes?

On particularly chilly days, some of the pipes in your house can be exposed to cold enough temperatures that the water inside them freezes. Mostly commonly, this happens to pipes close to external walls or the main water pipe leading into your house.

A frozen pipe be a nuisance when it slows or stops the water to your faucet, but the real danger is that it will cause the pipe to burst. Water expands when it freezes, which can cause it to grow bigger than the pipe containing it. All that pressure can eventually crack the pipe, causing a flood of water when the blockage of ice thaws.

How do you know if you have a frozen pipe?

Most often, you’ll know you have a frozen pipe when it’s below zero outside and you notice the water in one of your faucets has stopped or slowed to a trickle. To see which pipe (or pipes) has frozen, try turning on the other faucets in your house to see which ones have been affected.

Sometimes, you can actually spot the frozen pipe just by looking. Watch for pipes that are frosted over or bulging like a snake that’s just eaten.

What to do if you have a frozen pipe

  1. If you can see or suspect that the pipe has also burst, shut off the main water valve to the house to prevent flooding. To speed up the thaw, open all faucets in the house to allow air into the pipes to spread heat.
  2. If you don’t shut off the water, make sure you know the location of the main shutoff valve and that the valve turns easily; you may need to shut off the water quickly if water starts leaking when the pipe thaws.
  3. Crank up the heat in your house.
  4. If the water is on, turn on a cold water tap in your basement (a slow trickle is fine).
  5. If you know which area of the pipe is frozen and you have access to it, you can speed up the thawing process. Move a space heater nearby or run a hair dryer over that section of pipe. You can also wrap the pipe in warm towels or with an electrical heat tape. Do not use any open flame, like a propane torch, to heat the pipes—this is a fire hazard.
  6. Thawing can take up to a full day and there’s danger of flooding if the thaw reveals a cracked or burst pipe. Therefore, it’s important to have someone at stay home at all times during the thaw to supervise.
  7. Once the pipe thaws, run the water and check closely for cracks and leaks in the pipe.
  8. Be ready with a mop, bucket and towels to clean up after the thaw or in case of flooding.

Hopefully, you can catch and fix the problem before the ice damages your pipe. In many cases, however, you will have water leaking from the pipe after the ice is removed—the result of a burst.

What to do if you have a burst pipe

  • Shut off the main water valve.
  • Call a plumber to come and repair/replace the pipe.
  • To prevent water damage, clean up as much of the water as possible with a mop, bucket and towels. If you have a dehumidifier, run it until the space is very dry to prevent mold.
  • If there was a lot of water and you expect damage, you may need to call your insurance agent.

How to prevent frozen and burst pipes

There are many steps homeowners can take to prevent pipes from freezing. And they’re much less costly than repairing damage and replacing furniture after a flood!

  • Know where you main water shutoff is and make sure everyone else in the house does, too. This can save a lot of time and damage in case of an emergency. If you live in an older house that has a gate valve (which can stick when you really need it to turn), you might consider switching it to a newer, more reliable ball valve.
  • Make sure your pipes are well insulated, especially any pipes close to outer walls or in colder areas like attics, garages or basements. Foam pipe covers, available at most home improvement stores, are a good way to do this.
  • Seal any air leaks in your home to keep cold air out. The most common spots for air leaks are around windows, doors, dryer vents and pipes or wires that run out of the home.
  • Outdoor faucets are the most likely to freeze. Before winter, detach your hose, shut off the outdoor water supply and drain the tap.

What to do if the temperature drops and you’re worried pipes are freezing

  • Turn on a cold water faucet in your basement (just a slow trickle)
  • Open any cabinet doors that contain plumbing (like under a sink) to expose the pipes to more heat.
  • Keep your garage doors closed.
  • If you’re concerned that a pipe is starting to freeze, do what you can to warm it. Use a space heater or a blow dryer, or wrap the pipe in warm towels or electrical heat tape. Again, do not use any open flames because they’re dangerous.

How to protect your home from frozen pipes when you’re going away

  • If you’re gone for an extended period or during very cold temperatures, close the main water valve and open a cold water tap in your basement to drain any water left in the pipes.
  • Have a friend or neighbour stop by periodically to check on the house.
  • If you don’t shut off the water, you may choose to leave a very small amount of water running while you’re away (be aware that this will affect your water bill). Slightly open a cold water tap in your basement, like a laundry tub, and ensure the basin drain is clear to prevent flooding.

Are your pipes still prone to freezing, even after taking precautions? There may be a problem you’re not aware of—call a plumber to get it checked out.

Do you live in Toronto and have a pipe that has frozen and burst? Start the thawing process and contact Neighbourhood Plumbing to repair that pipe.