With respect, parent comment is right. It is "just" destiled water with some salts. You also have to remove dissolved gasses and store it in good bags. Tricky part are contaminants and paperwork.

We had similar situation in communist czechoslovakia. There was a plan to manufacture female hygiene products, in a single factory for entire country. This factory burned down on second year of five year plan. So for some time our ladies were forced to use toilet paper. We still managed to make IV fluids though!

My guess US planning is a bit similar. Too special to import medical supplies from neighbours or from Europe.