A few years back I travelled extensively in a FWC in the winter into Canada and the west. At the time we drained the onboard water storage and plumbing system and used a portable water jug for our water. We did this out of concerns for freezing/burst pipes, fittings.
I just bought an ATC bobcat and am again traveling extensively at the current time and throughout the winter. I am in the eastern sierra now but will be all over the west and possibly into Canada, AK, and the Northeast US. I have had temps in the teens and 20's for a few nights now without draining the onboard water system and seem to have no problem. I am thinking that with the heater and insulation that I may not need to drain the water. Does anyone have any experience with using the onboard water system in temps below freezing and possibly below 0 F?