Just put a sock on it...

Here in Montana, is still pretty cold!
Nights are dipping into the 20's and 10's so, even though the water hookup in the KOA is insulated, our hose, and especially our water filter, is getting frozen.

I got he "brilliant" idea of putting a sock over the filter to see if that helped against the freeze.
It did not. Instead, now I had to deal with a frozen solid sock that prevented me form unscrewing the fittings and filter.

Not a Nobel Prize entry...that's for sure.

Winter experienced RV'ers here pointed me in the right direction:

When the night gets this cold, unhook the city water and rely on your fresh water + pump + furnace to keep things OK.