I have a hard time counting in oz. but personnally, I'm at between 3 and 4 liters a day (4 would be in summer and on exercise days, especially cardio). I count all liquids in it, not only water, but most of what I drink being water based (tea or coffee without sugar or cream), it's almost the same. Well, probably.
I use the 'pee test' as well.
If the pee is not a light yellow, then it means I haven't drunk enough.
It's a double-edged sword though. Once you're used to drinking a lot, if one day you happen to reduce your intake drastically, you may experience nasty side-effects. Of course, upping the intake is good, if you weren't drinking enough before that! The other aspect of it just needs to be known.