This photo, of any empty bottle water aisle in Washington, D.C. is a bit disappointing, if completely predictable.
My solution, based on more than a few times through a hurricane, is to keep a covered dutch oven full of water on the stove, the electric kettle full and a pitcher in the fridge. And I’ll doubt I’ll have to depend on those.
I also make sure all the outstanding dishes and clothes are washed. (Clean clothes are no substitute for a shower should there be a real shutdown, but it does make making-do happier.)