I typically drink under 16 fluid ounces of fluids a day. It is never water or milk, always various juices, coffee drinks, and sometimes caffeine free sodas, but only pop when I go out to eat. When I do sports, I will drink from a 24 oz water bottle with straight water in it. Depending on how hard of a workout and how hot it is, I will drink anywhere from a sixth of the bottle to the entire thing. I always here that you are supposed to drink at least 64 oz of water a day and I am way under that. Is it a problem? I will sometimes pass out unexpectedly and my doctors have never been able to find a reason. They just say it is probably dehydration. But what they don't realize is that level of hydration is normal for me.