DrewE wrote:
A lot depends on how your RV is constructed with regards to cold weather operation.
...You do have to use water from the fresh water tank rather than leaving a hose hooked up to the campground water supply (connecting only to fill the tank and disconnecting and draining out the hose afterwards).
We kept ours hooked up through -1F temps last year using a Valterra heated water hose, and a segment of heat tape on the tap coming out of the ground. Never froze, and we kept the fresh water tank full just in case. In our case, all of the tanks have 12VDC heaters.