I let our water drip all night in fear of this.
Although there are three places where I'm subject to frozen pipes, the worst has always been the 2nd floor tub. Unfortunately, it has the type of single-control valve where if you put it on a trickle you'd only get cold water through, not hot, and both have been subject to freezing.
Usually, my only choice has been whether or not I need to get up in the night (to run the water for several minutes) once, twice, three times, or every two hours. I don't usually have a problem till it's -5° or so... last night (and tonight) are well past that...
