Answered by Stavros Kavouras, professor and director of the U of A’s Hydration Science Lab and adjunct professor in medicine at the University of Arkansas for Medical Sciences. The daily total water intake guidelines for American adults is 3.7 liters for males and 2.7 liters for females. However, this amount includes the water from solid foods (fruits, vegetables, rice, etc.) that accounts for approximately 20 percent of total water intake. Thus, the total daily fluid intake is around 3 liters (96 oz) for males and 2 liters (64 oz) for females. This amount includes water from all beverages. However, we have to keep in mind that a can of a soft drink contains seven teaspoons of sugar, which alone exceeds the daily added sugar limit recommended by the World Health Organization. Also, just one can of soda per day increases the risk for diabetes by 26 percent. Plain water is probably the healthier way to hydrate.