As you suggested, I will get more water. It’s cheap, easy to store, and a lot better to get now than to try and get after a disaster. Thanks for the advice!
Another quick question. When hooking up a portable generator with a bonded neutral, should the service transfer switch for the sub panel I plan to power, include just the two hots and neutral, but use the house’s ground, or should I also transfer the ground to the generator? If I do so, how will this effect any GFI protected circuits that may be on this sub panel?