We were advised by a dealer RV technician to winterize our water lines while driving in cold weather. The claim is that windchill would freeze the water lines while driving. When I review a windchill chart driving at 50 mph in 40 degrees F the windchill is 26 F. It sounds like every time we travel we will need to winterize water lines. —Tim Connors
Answer (from Mark Polk, RV Education 101)
What I recall from my research, the ambient temperature is the ambient temperature and cannot be changed by the effects of windchill.
For example, if the ambient temperature is 40 degrees with a windchill of 30 degrees, and there was warm water (70 degrees) sitting in the water lines of the RV, the water in the plumbing system would cool down to 40 degrees faster because of the windchill, but it would not go below the ambient temperature.
But, if the possibility exists that temperatures could drop and stay below freezing at some point while getting to your destination, it will freeze.