Yellowstone Next Week - Freezing Temps Concern

Water freezes at 32, but where does affluent freeze?
For damage to be done your valves will need to freeze solid, and temps will need to be lower than 30 for a long time.
The solids will not expand like water when frozen, so that is good, but they contain high % of water still.
You will need some sort of tank heater (stick-on heating pads) if you do this a lot. You will need power though.