Likely cause: a frozen section you can reach

Why this happens

The American Red Cross and Moen both say that a trickle from a faucet suggests a frozen pipe, often against an exterior wall or where the water service enters through the foundation. The City of Winnipeg says the frozen area will show frost or ice and that slow, even heat is the key to thawing safely. The sources disagree on electric heat. Moen and the Red Cross allow a hair dryer, a heating pad or a space heater kept away from flammable materials, while the City of Winnipeg says not to use hair dryers or portable heaters because they are fire hazards. So this page sticks to the methods none of the sources we opened warns against for electric heat: an open faucet, a warmer room and towels soaked in hot water. This Old House names the towels for partial freezes and recommends a plumber for a pipe that is completely frozen, while the Red Cross, Moen, Protect Your Pipes and the City of Winnipeg give thaw steps without that limit. If you are unsure, or the thaw is not working, stop and call a licensed plumber.

How to fix it

1. Safety first. Never use a torch, a kerosene or propane heater, a charcoal stove or any other open flame. The Red Cross and Moen name those, and This Old House says never to use an open flame. Stay out of standing water and keep every electrical device away from wet floors and wet pipes.
2. Look over the pipe and the floor. If you see a crack, a drip or pooling water, stop. Close the main by hand if it turns easily and call a licensed plumber.
3. If every tap in the house is dry, close the main shutoff first, as Travelers, Protect Your Pipes and This Old House advise. Turn it by hand only, and never force it.
4. Open the faucet closest to the frozen pipe and leave it open. The Red Cross and Moen say running water through the pipe helps melt the ice. If the whole house is dry, Travelers says to open all the faucets.
5. Open the cabinet doors around the pipe and turn up the thermostat, as This Old House and Family Handyman suggest. The Red Cross says to move cleaners and chemicals out of children's reach first.
6. Wrap towels soaked in hot water around the pipe. Let the water cool enough that you can wring each towel out without burning your hands, so water does not drip on the floor. The Red Cross and Moen name this method, and This Old House names it for partial freezes. The City of Winnipeg says not to use boiling water because it can cause the pipe to burst. Start near the faucet and work toward the coldest section, as Family Handyman and the City of Winnipeg describe, so the melting water can escape through the open faucet.
7. Keep warming one section at a time, and make sure each section has thawed before you move on, as This Old House says. Keep the faucet open the whole time. Moen says to apply heat until full water pressure is restored, and you will only see that once the main is back on. Until then, This Old House says to warm the pipe to room temperature, and the City of Winnipeg says the frozen area shows frost or ice, so look for the frost to be gone before you open the main.
8. Once the pipe has thawed, slowly turn the main back on if you closed it, with the faucet still open, and check the pipes and joints for leaks, as Travelers and Protect Your Pipes advise. Travelers says to be ready to turn the water off right away if you find one. Check your other faucets too, because the Red Cross says that if one pipe freezes, others may as well.
9. To keep it from happening again, leave the cabinet doors open and let a faucet served by exposed pipes drip when it is very cold. The Red Cross, Travelers and State Farm all suggest this.

When to stop. Stop and call a licensed plumber if you cannot find the frozen area, cannot reach it, or cannot thaw it, as the Red Cross and Moen say. Stop at once, close the main if it turns easily by hand, and call a plumber if you see a crack, a drip or pooling water. Never force a stuck shutoff, and keep clear of standing water near anything electrical.

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