How to stop water pipes freezing in winter, and how to thaw them safely

These sources are from the United States and Canada, where houses are built for hard frost. We found no Afghan water-utility guidance that we could open, so the page gives general rules. Pipes in Kabul, Ghazni or Bamyan may be laid differently, and a local plumber knows your house.

Where pipes freeze first

• Pipes along outside walls and water lines in unheated outbuildings are at most risk (University of Missouri Extension).
• Fredericton lists the usual spots: exterior walls and the place where the supply line enters the house through the foundation.
• Outdoor taps and hoses freeze too. DC Water says to remove, drain and store garden hoses.

Before the cold: five things to do

1. Insulate the pipes. The Missouri expert calls extra insulation the first choice. DC Water suggests a "pipe sleeve" from a building-supply shop for pipes that are not insulated.
2. Shut off and drain the outdoor tap. Close the inside valve that feeds it, then open the outside tap so water left in the line can run out and has room to expand (DC Water).
3. Open the cupboard doors under sinks so warm air reaches the pipes (Missouri, Fredericton).
4. Seal drafts near pipes, such as basement windows, and keep garage doors closed if water lines run there (Fredericton).
5. Keep the room warm day and night. Fredericton advises the same heating setting through the night. If you leave the house for a long time in cold weather, keep it above 55°F (DC Water), which is about 13°C (Fredericton says no lower than 13°C).

Photo: Todd Huffman from Phoenix, AZ · CC BY 2.0

If you heat a room with a stove, brazier or gas heater, read how to heat your home safely first: the gas from burning fuel in a closed room is a bigger danger than a frozen pipe.

Missouri also suggests a shielded light bulb placed near a pipe, kept away from anything that can burn.

Should you leave a tap dripping?

The sources disagree.

• Yes: DC Water and Fredericton both say that in very cold weather you should let cold water drip from taps served by exposed pipes. Moving water is harder to freeze.
• No: the Missouri expert says not to let water run to prevent freezing, because it can affect water pressure and firefighting supplies across a supply system.

Both are written for towns with a piped network. Where you carry, buy or pump your water, the water you lose is a cost you must weigh yourself. Insulation and warmth are advised by all three.

If a pipe has frozen

The sign is a tap that gives only a trickle or nothing (Fredericton). Then:

1. Open the tap so water can flow as soon as the ice melts, and so pressure is relieved (DC Water, Missouri).
2. Warm the pipe gently. Fredericton lists an electric heating pad, a hot-water bottle, a hair dryer, towels soaked in hot water, or a portable space heater. Missouri names a light bulb or a blow-dryer and says to thaw at the same rate the pipe froze. The hot-water bottle and towels need no electricity.
3. Keep heat clear of anything that can burn, and never leave a heater unattended (DC Water, Missouri).
4. Keep going until full pressure returns (Fredericton).
5. Check the other taps. If one pipe froze, others may have (Missouri).
6. Know where the main water valve is. A pipe frozen for hours may leak once it thaws (Missouri). If it leaks, shut the main valve.
7. Call a plumber if you cannot find the frozen part, cannot reach it, or cannot thaw it (DC Water).

Never use a flame to thaw a pipe. DC Water: "do not use any open flame devices." Missouri names blowtorches and kerosene or propane heaters, which heat too fast and can break the pipe, and adds that plastic pipes turn brittle in the cold and can burst before copper. A flame also means fire, and in a closed room it means carbon monoxide. We found no source on a coal brazier held to a pipe, but it is an open flame, so do not.

Next steps

Check the night's low on the weather page and prepare pipes the evening before a frost. If someone is poisoned by a heater, the emergency numbers are on the site.