Excellent, fair question. I've never really measured how much I imbibe.
Let's see -- when left to my own devices, just listening to my body:
6-7 oz. of OJ in the AM and a little bit of cereal/milk.
For lunch, I may include 6 ounces of liquid (pop or hot chocolate).
For dinner, maybe 6 oz. of something but sometimes nothing to drink.
Later in the evening, maybe 10-14 ounces of assorted juices (apple, cranberry, or grape).
HOWEVER, in the last year I have reduced drinking pop (soda for those of you out East). I try and drink more water -- usually a 16.9 oz. bottle. I have that on my desk when I'm teaching and it helps with the voice, too. Also, I forgot to add that I work out 2-3 times per week and I do down another 16.p oz. bottle of water.
That's a very rough estimate.