Was going to ask my LOR about this, but figured I'd get the crowd mind's opinion too. A lot of people drink Electrolyte infused drinks prior to a fast. There is a company called NUUN that makes electrolyte tablets that can be used to turn a glass of water into an electrolyte drink. The tablets work like Alka Seltzer. You drop them into the cold water, and within a minute or so they turn the water into gatorade/powerade.
What would the potential issues be with making this on Shabbos?