I used to put gatorade in my bottle, when they stopped carrying the ones I liked at costco, I just went with water. No difference in performance for me at least. If anything, these "sports" drinks are good for encouraging you to drink more, other than that, I don't think the added electrolytes make a big difference unless you sweat a ton and are doing some sort of crazy endurance training. That's been my experience anyway. The added hassle of cleaning the bottle more thoroughly does not justify the added cost or perceived benefit. But I'm lazy so take it with a grain of salt.