The underbelly is heated and it's supposed to be a 4 season RV. But I was looking at mine this evening and it hit me. The grey water drain pipes and both the grey and black water valves are under the camper and exposed to outside temperatures. So I would think if the valves are closed water would be in the lines and freeze when temperatures drop. I would also guess they would probably burst the piping and valves?? In my camper that I just sold all piping and valves were enclosed in the underbelly. Am I correct in thinking this is a big problem? Not sure why you would heat the underbelly but leave the drain pipes exposed.