If it only periodically drops below freezing, it's pretty unlikely it'll freeze through the pipes. I've been in winters cold enough to freeze running water, winters so cold that it was frozen 3-4 feet into the ground. I remember once it even got so cold that F and C read the same number on the thermometer. That's d*** cold.
But if it's just dipping below, you should be fine. That's not real cold.
Dan