mostly just water but if I need electrolytes I’ve found most pre-made powders, tablets, or drinks are too sweet, more so if they use alternative sweeteners like Stevia. so, I found a place that sells electrolyte powder, unsweetened and unflavoured, and mix it up myself with some water, lemon juice, and a bit of Stevia. much better than the premade mixes.

although I do like pocari sweat as a rare thing. you can buy that as a powder online, but the local asian market sells cans of it so I keep a few around.