@Spence, coasts are where the highest concentration of people are… if we get a situation so dire you need to extract your own salt, you are not going to want to be where people are concentrated.
@Dr_Richard sand pots work well in low humidity areas… not so much in the midwest. In dryer climes the evaporation works well but they have to be maintained wet, and the places they work best (deserts) may have a water supply problem.
Water storage can work, but “down a well” … not so much. There are very few wells of the “bucket on a rope” variety… most are a 6" or so hole and the water is 30 to hundreds of feet deep. With a well pump in them. Besides, if you lost a bag of food down one, now that rotting food will contaminate your water supply. Plus if that’s your water supply, and you were prudent enough to plan for a suitable well-bucket and mechanical winch, that space is going to be busy.
If you have access to deep water or snowmelt or groundwater where it surfaces, maybe you can use that, but you now have to deal with scavengers.