Yes, they can, but usually do not. Although there have been isolated incidents of frozen pipes here, it is not something to become overly alarmed about. But you should know if you have any pipes that may be susceptible in the case of a hard freeze. Pipes that have frozen in the past are often attributed to solar panels installed on rooftops with faulty freeze protection valves. The pipes would burst in the early morning hours when it is the coldest and when there is no water moving through them because members of the household are asleep.