I worry about our hot tub. Even at zero degrees outside, ours supposedly won't start freezing for a week or more (I'm not sure I believe that though). We could drain it, but then the back yard would turn into one gigantic ice rink. Unless you have a really big generator, backup power is not an option. 220v at 50amps is what the tub uses when the heaters and pumps are going, and you can't heat without the pumps running too (pumps don't have to be at full power though).

Another recommendation I've heard is a 120v submersible sump pump on a small generator with both the pump inlet and outlet under water. The heat of the motor supposedly keeps the tub from freezing. That would circulate water in the main body of the tub, but I am more worried about the plumbing lines freezing. A sump pump wouldn't circulate through the plumbing. I guess I'd try the sump pump, but if that appeared to not be working, raise the outlet and use the pump to quickly drain the tub. And just deal with the resulting skating rink.

I'd be interested to hear what other tub owners plan to do during extended power outages.

OK, we've moved from cooking with no power, to heating a house with no power, to maintaining a hot tub with no power. In a normal situation where we know the power will eventually come back, cooking would be my least concern. But at the end of the world when power would not be coming back, the hot tub would take last place in the concern department.