I found the study! It came out of Nebraska.

Two groups were compared--urinalysis and maybe blood tests, too, of caffeine drinkers and water/juice drinkers. Results: both groups were pretty much equally hydrated with the water/juice people doing a bit better, but not enough to make waves.

I'm sticking with my 4-5 cups of coffee during the day and the shot or two of bourbon at night. I detest water except when very, very thirsty.