Just spitballing here, can't you just store the salt alone and make the hyper-saturated salt water on the fly? That seems reasonable.

How do you get the salt to make the brine? You'd need to evaporate the water from the brine which means you either need very large evaporation pools or lots of energy to boil the water (and money to maintain the immense amount of scale you create).

Salt mines.

Here’s one in the USA:

https://youtube.com/shorts/zXzvUKXhMBo

Here’s a list of salt mines in the USA:

https://en.wikipedia.org/wiki/Category:Salt_mines_in_the_Uni...

Build a water desalination plant next door. Make it a twofer

Agreed, considering that sor.say future wars will be around (drinking) water it seems reasonable to at least link some cost to the brine or the water required.