Keep water lines from freezing

Available in northern climes, though perhaps not in Arizona, are heat tapes specifically intended to go on exposed water pipes. They contain internal thermostats set to keep the tape at 35 degrees, just above freezing. You may have to google them, but they are widely available at home improvement stores. I used to see them all the time in Ohio, but not so much here in Virginia, we have to look for them. It should be noted that they should NEVER be place such that the heated part overlaps itself. In some applications, the tape is run along the pipe, in others, it wraps around the pipe every few inches. The tape will have instructions, be careful to follow them lest the tape burn itself up.