1-Remember this, when it comes to water...my botany professor was a hiker and always carried IODINE, which only a drop or two per gallon will purify water enough to drink.
2- You can take a bucket of rain or river water and pour fast into a toilet and it will give enough pressure to flush it.
3- Be sure to stock up on candles, “lamp oil”, and purchase a couple oil lamps or camping lamps. Batteries may not be available later on.
Dried foods like oatmeal, rice, beans are good to have, and put a few bay leaves in any open bags or containers to keep out bugs.
Error on the amt of Iodine, do internet ressearch, but I think it’s 5-6 drops pr 32 oz...but check it out.
Have barrels you can put underneath your downspouts to collect rain water.
Nam Vet