I carried a canteen cup even after I quit carrying canteens (and I caught hell for that, as it was SOP to carry two. Try explaining to your 1SG why a camelback was better before they became issue.)

The cup has many uses, least of which is to drink from. The one thing I don't like is that it cools the liquid too quickly. I'm going to be painting mine black and see if that helps any. I also have a stove - cheap aluminum cup shaped, carried it on my other canteen, then w/ the cup). I found that by canting the cup so it doesn't fit directly helped when trying to seperate the two.