text: Ive always been told typically a gallon which is 128oz.  I think if you add gatorade mix to it thats okay but atleast half of that should be directly water. But mom always said a gallon a day.  I never drink that much though. Milk has alot of water in it too.  Stay away from carbonated beverages, and high amounts of sugar you should be okay.  Ice Tea is tasty!