I carry a roll of Nuun in my bag. I like the form factor -- makes for easy storage.

I recall watching a video -- I think it was part of the Talks @ Google lecture series which covered heat exhaustion and dehydration and they talked about what to look for in a drink electrolyte supplement.

After that, I went out looked at different supplements and found Gookinaid Hydralyte (now Vitalyte) matched their requirements.

Lately I haven't found it in the stores and so have been getting Nuun which looks pretty close and is available at my local REI.

I really wish I could find that video. It had some real good coverage about heat exhaustion, heat stroke, dehydration, etc. It was sort of hiking medical oriented.

-john