That is essentially the choice I am facing. I am now at the cusp of this cold snap and according to one weather source it will get down and live below -20C but according to two others, and local weather stations, at its worst it will just dip below -20C.
I plugged in last night and ran my electric heater and furnace and I was toasty warm all night and the water still flowed. The furnace and electric heater were not maxed out nor was the furnace constantly running. I am sure I can be fine down to -20 while plugged in, much colder than that I will surely have problems.
So I must decide today to drain my tanks or not. I will still buy what I need for my makeshift toilet, just in case. I have a feeling I will be fine as I can run the furnace at its lowest setting all day (+5C) and leave it run. Then at night I can run it a bit higher and wait to plug in where I can run the electric heater and turn on my heat tapes for the tanks.
I can’t really check what Wanda is rated for as RV manufacturers will not tell you a temperature, as they would be liable if things go wrong. At least I have not been able to get a straight answer from them. One salesman told me south of -10C and you will have problems, but I think that is conservative.
I will take the risk and not drain my tanks, but if it looks like it will get much colder than -20C I will drain my tanks and switch to my “backup toilet and graywater tanks.” As in two buckets, one to fill with sink and dish water (to dump later) and the other to be used to hold a garbage bag so I can “do my business” in.
I did pick up a few other warm clothing items that I needed. I couldn’t resist this classic number.
I will take this cold snap day by day and see how things go. I hope I don’t regret this but I can’t be afraid of anything below zero. If I am to stick this out, I need to find a way to cope with the colder weather. The true decision is to determine how cold it can get with water in my tanks and lines, before it gets too cold and that water freezes, or it becomes economically unviable to keep the tanks liquid.
I a tough, I have lived on the prairies long enough to have worked out in really cold weather. I can deal with this, the question is, can the water tanks handle it, and if so, how much can they handle?