Hi Tammie,
We're getting ready to head out to the Colorado mountains for our 4th extended ski trip in our Landmark. We use the water systems in our rig down to -30F, but purchased options like the tank heating pads, fireplace, and dual pane windows and have done some modifications to keep water running in freezing temps. We have added heat tape to all of the water lines in the coach, gate valve heaters, extra insulation, and of course use a heated water hose.
One thing we still have to do is evacuate water from the refrigerator's icemaker/water dispenser feed line, solenoid, and lines in the frig. Because the refrigerator is in a slideout, the water line has to be routed under the slide, and is exposed to outside air. That line will freeze as soon as temperatures go below freezing. On our rig, the solenoid on the back of the frig is heated, but can also freeze in extreme weather, or in a storage situation where AC power is off. So while the coach is 4 season, the icemaker is not.
If you'd like more information about winter usage, in the
manuals section of the forum we have an
owner-written Water Systems Winter Usage Guide that may be helpful to you.