The technology commonly known as the heat trace is a type of tape that can be applied to a pipe heat it and prevent it from freezing in cold weather. This technology can be commonly found in homes that are not properly insulated to prevent pipes from freezing in the winter. The use of this technology allows for the home owner to avoid the added expense of insulating and heating the areas where the pipes are located. We see this often in rooms that have been subsequently added on to houses after its initial construction. As such we see this commonly in older homes and in lower income areas.
This was exactly the situation I experienced in the first house that I owned in in the Roxborough area of Philadelphia, Pennsylvania. My wife and I bought a row house with a room that had been added on to it in the back subsequent to its initial construction. This added room happened to be a bathroom with a shower and toilet. The first winter we lived in this house we discovered that the extra room was not properly heated or insulated. Because of this the pipes supplying water to the shower froze and burst.
Had my wife and I been more knowledgable home owners we would have realized the impending issue we would have to face. We did know that the room was improperly insulated because it was much colder than the rest of the house during the winter. We did not however put two and two together and realize that we needed to do something to prevent the pipes from freezing. The use of a heat trace could have potentially solved this problem. Also running the water at a low level seems to also work but not at extremely low temperatures.