A frozen pipe should be thawed with gentle heat, such as a hair dryer, a heating pad or hot towels, with the tap left open. Never use a flame. If you cannot find the frozen section, if it is inside a wall or underground, or if the pipe is split, stop and contact Wilfrid David, the plumber in Chénéville who thaws frozen pipes throughout La Petite-Nation.
Before you apply heat: two things to locate
It is best to know where these two things are before a cold snap arrives.
The main water shut-off. A frozen pipe is often already cracked. As long as the water is ice, nothing leaks. Once it thaws, water escapes through the crack, and you will need to shut off the supply quickly.
The pump breaker, if your property is on a well. With a well, when a pipe bursts, the pump keeps pushing water as long as it has power. Close the valve and, if necessary, switch off the pump. Locate both ahead of time rather than in the middle of the night during a leak.
Next, open the tap that has stopped running. You will see water start to flow as the ice gives way, and moving water helps melt what remains.
Find the frozen section
Pipes freeze in the same places almost every time: along an outside wall, in the crawlspace, in the garage, under a counter against a north-facing wall, or where the line enters the building. Run your hand along the pipe. The frozen section feels colder than the rest and sometimes has frost on it. Copper or PEX pipe that looks swollen is a warning sign, as it may already be split.
If only one tap is dry, the ice is between that tap and the point where the lines branch off. If the whole house is without water, look at the water entry or the line from the well. Our article on no water at the cottage will help you narrow it down.
Thaw the pipe gradually
According to CAA-Québec, a hair dryer remains the most effective method, and it is the one we recommend as well. Start near the open tap and work toward the frozen section, keeping the heat moving so that no single spot is overheated. A heating pad wrapped around the pipe also works, as do towels soaked in hot water if no electrical appliance is available.
This takes time: allow one to six hours, depending on the cold and the length of pipe that froze. Never leave a heating appliance running unattended.
Once water is flowing, keep an eye on the pipe for at least an hour. A crack often only becomes visible once pressure returns to the line.
Take care with electricity as well: keep the hair dryer away from any standing water, do not stand in water yourself and, if possible, plug the appliance into a GFCI-protected outlet, the type with a test button.
Methods to avoid
Never use a blowtorch, a propane or kerosene heater, or any open flame. These present a risk of fire and carbon monoxide poisoning. Cottage walls contain dry wood, insulation and dust, and a fire can smoulder inside a wall long after the work is done.
CAA-Québec advises against using a torch, especially on plastic pipe: PEX melts. We also advise against heat guns, which concentrate too much heat in one spot and lead to the same result on plastic pipe.
When to stop
Stop and contact a professional if:
- you cannot find the frozen section;
- it is behind a finished wall, under a slab or in a crawlspace that is difficult to access;
- it is the buried water line between the well or the street and the building;
- you see a split, a bulge or water seeping out;
- nothing has changed after several hours.
If the same spot freezes every winter, it is best to address the cause: improve the insulation, keep some heat in that space or install a heat cable. Our article on where heat cable goes and how to tell if it is working covers the details. If you are leaving the cottage for the winter, CAA-Québec recommends keeping it at 10 °C or higher.
When to call a professional
For a split pipe, ice inside a wall or underground, or no progress after several hours, call us at 819-428-3161. We thaw the line and repair any damaged sections. Evenings and weekends, emergencies are handled on call. For more information, see our pipe thawing and heat cable page.
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