OK..so the water issue was addressed.
Now air quality.
Who knows what might happen..but those 3M half face masks with the filter cartridges are relatively cheap and can be hung on a hook in a closet.
Warmth...gotta have a woodstove
The most important tool to keep your wood stove fed most would agree is a chainsaw.
[and a splitting maul and a few steel wedges...maybe even a cart to haul with.]
If you don't have a few spare chains, pull rope assemblies [the whole enchilada, with the spring loaded "pawls"] and a spare clutch..then order them now.
2 cycle coil and gasoline stabilizer for long term storage.
I would like to own a 2 Man Buck Saw for a back up "system" and of course you need all the hand tools to keep this equipment sharp.
I don't see how people will manage without 5 acres of wooded land that is distanced at least a few hundred miles from the nearest high density population.
Game will be in short supply, so having a few buckets of Wheat, Barley, Oat, Rye Seed is not just good food for us but also a way to attract those 4 legged animals that will be in short supply.
I would try to capture breeding stock of wild rabbits if finding domestic rabbits for sale or trade was not possible. They only need to eat weeds and to live on clean ground in movable cages.