When I was young and in college, I don't recall drinking much water. I do recall when there was a study about the benefits of drinking eight 8 ounce glasses of water a day. I sat down one night and I drank all 64 ounces. Boy did I need to pee after wards!
Now all I drink is filtered tap water. I have a charcoal filter on my fridge and keep a liter and a half bottle of water in the fridge at all times. I try to drink at least one 1.5 liter bottle each day. The bottle is a good measurement for me as to how much water I am drinking each day. If I get sick, I double my intake to try to flush out any toxins. Water really does not taste good to me when I am sick so I have to force myself to drink it. Also, my rule of thumb is that I drink one glass of water for each martini if I have one in the evening
I rarely drink sodas. This summer I have been brewing some decaffeinated iced tea sweetened with Splenda and fresh orange slices.