When weather is very cold, water in pipes exposed to outdoor temperatures may freeze. The first sign of this condition is blocked or reduced water flow at faucets. If you don’t act quickly, pipes may burst.

Finding the blockage may be difficult. At the first sign of a block, open the faucet and follow the supply pipe from there to where the pipe passes near exterior walls or runs outside of heated areas.

Melting the ice is easy, using any of several heating devices: a heat gun, hair dryer, heating pad, heat lamp, or, in a pinch, a propane torch (be very careful to shield flammable materials from the flame). Leave the faucet open so water can drain.

After the ice has melted and the pipes have cooled down, prevent them from freezing again by jacketing them with foam insulation sleeves. Put pipe insulation around all the pipes that pass through unheated spaces to protect them from freezing. On outdoor pipes, insulation should extend about 12 inches below the frost line, which represents the average depth at which soil is likely to freeze year after year.

To prevent pipes from freezing in the first place, there are a few things you can do:

• Make sure outdoor pipes are buried below the frost line. If they’re not—and your home is in an area that has frequent freezes—you may want to consider having this work done by a qualified plumbing contractor.

• Insulate pipes that are exposed to the outdoors or that run in unheated crawlspaces, basements, attics, and walls. To insulate them, you can buy tubular, sleeve-type foam insulation that’s slipped onto the pipe like a jacket. Simly cut pieces to length with a utility knife.

• Insulate the cavities where water pipes run—between floor joists and wall studs, for example.