If you can keep it sterile, your mix should be a good general purpose thing to have about. It should have a way decent job as an electrolyte booster.
Yeah. I suggest keeping the ingredients handy, and mix as needed, making it easier to keep clean/sterile.
Something every survival-oriented person should know, IMHO: Oral rehydration therapy.
http://rehydrate.org/solutions/index.htmlJeff