Pkat also pointed out (thanks, sweetie! =) that when "they" say to get 8 glasses of water per day, they meant 8 x 8 fl. oz. glasses. I know that a standard can of pop is 12 fl. oz. or 355mL. My water bottle is about 700mL, so my water bottle actually counts for just under three glasses of water.
This would mean that my usual 6 bottles of water should be plenty. =)