I grew up in Iowa on a farm that when the water line in the ground was put
in was not deep enough in spots. On the coldest nights Dad would leave
the
water tap on just a crack so that the pump would come on a few times a
night. Seemed to solve the issues on the really cold nights.

Which would only work if something was pumping the water along. Should
power go out you're still stuck.

If it's going to remain unheated and unoccupied then the only sensible thing
to do is drain the lines.