Does it have aspartame? If so, there's a long article on that below.
If you get sick of water (I do sometimes too), try soda water (just plain carbonated water) and/or water with lemon or lime slices... you get some flavor & a vitamin C boost too!
I think its still confusing as to whether or not aspartame is evil or not. But I think a general rule of thumb to follow is "moderation in everything", except water of course.
As with mixing soda water w/ lemon or lime. mixing 1/4 cup of juice works too -- cranberry & soda water is good when you just can't do water anymore. And there's nothin funny in it.