These haven't really been invented in the UK yet and I miss them terribly. Hopefully the day will come when I don't need to smuggle on 6 months worth of Crystal Light packets in my carry-on The dollar store carry nice ones, some have a kind of dry, nasty aftertaste but plenty don't.
since i spend so much time in a 40 degree room (celcius) i take nuun (google it). it's an electrolyte supplement, but also comes in at a hefty 3 cals a tab which is meant for 500 ml of water, but i put it in my litre water bottles often. they do not taste chalky, or powdery and are not too sweet- as i find the crystal light ones are.
also you're getting the benefit of added hydration, and no sweetner!!