Frozen and Split Pipes
In colder climates, pipes located in exterior walls, crawl spaces, and attics are often subject to freezing. The best preventive measure is to insulate these pipes. Even insulated pipes can freeze when exposed to drafts of extremely cold air. When pipes freeze, a plug of ice forms in a small section of the pipe and expands, swelling the pipe, and, in most cases, rupturing the pipe wall. Even a well-protected pipe may crack after years of use.
A sure sign that a pipe has frozen is that no water passes through the pipe to the faucets nearest the freeze. You will often be able to feel along the pipe and locate the frozen area.