Great story.
I did the bathtub once and the water leaked away slowly, so I bought one of those water bags that fit in the tub. I haven't used it yet, thankfully. My mother and sister both said the water doesn't go out if the electric goes. I don't believe it. What I did find after Sandy was if your electric was out you could drive down the road until you hit a place that had it and grab some dinner, at least.
I didn't realize the sewers could be an issue. So you have to put water in them if they drop or will it suck out everything you put in?
Glad I filled up the car because a third of the nation's gas supply could be under water for awhile.