Re: Holding tanks freezing?
We lived full-time in our Class C in the Tri-Cities area of TN (Johnson City/Kingsport/Bristol) thru the winter of 2007/2008. We placed an old water bed heater pad we had under our exposed fresh tank, then wrapped that in the housetype insulation sheathing (pink stuff or blue stuff... depending on brand) and set the thermostat on as low as it would go. For our water hose hose, we laid one of our heavy duty 100 ft extension cords alongside out 100 ft water hose (yes that was way too long but that was as close as we could get to the house that we were working on), wrapped the cord and water hose in foam pipe insulation (get at least one size larger than your hose diameter) and duct taped the pipe insulation closed. I used pipe heat tape on our water filters (they sit in a 5 gallon bucket lined with Reflectix) and on the 4 ft drinking water hose (also wrapped with pipe insulation) that goes from the filter bucket to the city inlet valve on the Class C. The City inlet and the hose bibb on the house had a foam hose bibb cover on them. We ran electric heaters in the RV so the extension cord stayed pretty warm all winter. Yes it did freeze and snow... often. The pipe tape says to not use on water hoses but we haven't had a problem with it. We also spent the winter in the SW NC mountains in 2008/2009.
For the bus... we will insulate the fresh & holding tanks. Not for freezing weather (which we plan on never seeing again) but for the heat. Our fresh tank on the Class C has a just a thin layer of insulation on it. The water gets so hot while traveling, that I do not need to run the water heater... and I really like HOT showers! The waste tanks... cook (yuk). I still have the pipe tape we used (it will get re used on the bus... just in case). But I don't think we will need to heat our fresh tank. I do want to go to the Grand Canyon and the best time is supposed to be fall and spring but it snows/freezes then at times. That is the only reason we will set up for short term freezes... just for high altitude or late fall/early spring trips.
As for tank size, we are ending up with three 36 gallon tanks (fresh/grey/black). We have found that we don't have room for everything under the bus and have HUGE tanks as well. But we tend to stay in campgrounds and really only need to be without hookup while traveling. We will only wallydock a few nights before pulling into a campground anyway. My fresh tank will auto fill while hooked up to "city" water... we run all fresh water thru our filters now and the filters really knock down the water pressure so we just fill the fresh tank and pump from that. We can dump grey/black while in campgrounds or at dump stations. I'm using 18 gallon grey/black tanks now. They are good for about 3 or 4 days. We will probably not ever need to stay more than 1 week with out being able to dump tanks... but I still have my old tote tank (need to get the four wheeled kind... easier on my back). I can make several trips if need be.