At what temperature do you have to worry about pipe damage?

[ShrimpBurrito]

If you're going to let the inside go down past freezing, you'll obviously want to drain all the water lines AND make sure you run the water pump dry. If you don't, the ice will puncture the thin membrane/diaphragm inside the pump with holes you can't see with your eye, making it useless until you replace the diaphragm. (a $15 part that no brick and mortar store usually stocks)

Dave