[tentcamper]

Redtail Cruiser. At our last CS of a trip, before leaving, I open the drain and all the low point drains, and leave them open. On the return trip every hill, braking action, etc.. drains a little. By the time I get home there almost no water left in the tank. I do it so I don't have stale water in the tank at the start of our next trip.

If I had a little water in the tank, I'm with Bill that there room for the ice to expand and would not be concern.