Water freezes in pipes when the outside temperature falls low enough to form ice, and stays at that temperature long enough to penetrate the pipes carrying water in a house. Pipes running through a basement, crawl space, or an exterior wall have this happen the most.

When thawing pipes one needs to take into consideration how to thaw the ice within the pipe without compromising and bursting the pipe, and to that end, what kind of pipes there are in the building.

A propane torch or a hair dryer can be used to thaw ice in piping. Propane torches can be dangerous as they can do damage to the piping if not used correctly, and can also start a fire. They are, however, the fastest way to defrost pipes. Plastic pipes require hairdryer usage in thawing. Fire will melt the plastic and cause more problems than are necessary for such a minor inconvenience. Copper or metal piping may have hairdryers or torches used as a means to thawing. Whatever tool is chosen, slow and steady sweeping motions are used to distribute heat evenly so the ice inside the pipes thaws without causing problems such as bursting or cracking, making replacement of pipes necessary.

Interior pipes, such as those under sinks or along the inside walls of houses can be thawed by hairdryer or by leaving faucet turned on and letting the natural warm air of the house thaw out the problem. Especially if the pipes are under a sink such a kitchen or bathroom, this way is effective.

Thawing pipes is time consumptive work and it takes patience and, if pipes are being thawed by employing methods other than natural hot air, caution against attempting quick thawing that can compromise piping.