I’ve read that the two most important items during Katrina were water and plastic bags.
I can understand the water part, and plastic bags are useful, but I can’t see why they were so important...
Most people don't have duffle bags. A contractor grade plastic bag can serve the same purpose. When I go canoing, I seal my wallet inside a ziplock bag and put it in my pocket.
After a storm like that there is debris everywhere - you need the bags to clean it up. I have about 40 trees on my property, lost 3 in the storm, plus about 50 large bags of tree leaves and branches had to be picked up.
They were used to make large chunks of ice by people that had power for their neighbors.