Just so some readers donít get the wrong impression, it should be noted that eventually even moving water will freeze.
Once water reaches 32 degrees it freezes, period. The movement just prevents the localized cooling that would occur at certain points in a tank if the water were calm. With the water mixing during movement, you have to cool virtually all of it before any of it will freeze. In calm water, the water at the coldest point in the tank will freeze much sooner than the water at the warmest point in the tank.
In spite of that, during most travel the water in the holding tanks wonít freeze because it doesnít get cold enough before you stop and warm it up with the furnace. It would have to be exceptionally cold, and you would have to stay on the road for a long time before a full tank would freeze.
A full tank will remain liquid longer than a partially full one, since there is more water to cool down.
2012 New Horizons Travel Trailer (formerly an Airstream owner)
2008 Dodge 2500 diesel with Equal-i-zer hitch.