So, how much should we drink? The U.S. National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is: About 15.5 cups (3.7 liters) of fluids a day for men. About 11.5 cups (2.7 liters) of fluids a day for women.
According to H.H. Mitchell, Journal of Biological Chemistry 158, the brain and heart are composed of 73% water, and the lungs are about 83% water. The skin contains 64% water, muscles and kidneys are 79%, and even the bones are watery: 31%. Each day humans must consume a certain amount of water to survive. By the time we feel thirsty our body is already dehydrated and potentially suffering some of the effects and simply drinking to eliminate the feeling of thirst does not fully hydrate the body.
The best indicator of good hydration is urine colour, a pale straw coloured urine being a reliable indicator of good hydration. Darker coloured urine is a sure sign that the body needs more fluid. Getting into the habit of drinking regularly is a great way of keeping hydrated.
Some folk count all that they drink as hydrating - however, we have to remember that caffeine acts as a diuretic. Here in Arkansas we have the best water that I've ever had, so it is not hard to find a quality supply - it's just getting into the habit of drinking to avoid dehydration!