The formula I read for a while for daily water intake was your body weight in pounds, divided by two -- whatever that number, drink that many ounces per day. i.e. I weigh 125, so should drink about 63 oz./day (which is fairly close to the "8 glasses a day" recommended by most people).
Then I started reading more about what your question addresses: that we don't have to drink so much water and that it can cause good things as well as bad to leave the body!
I am curious to see what others will say about this.