Institute of Medicine Daily Fluid Intake Recommendations:
Males: 13 cups (104 ounces) per day.
Females: 9 cups (72 ounces) per day.
**A portion of this fluid is obtained through your food**
Exercise Fluid Recommendations:
In addition to the normal recommendations
3-4 cups (24-32 ounces) of water for each hour of exercise.
Other factors that may increase your fluid needs:
Heat and humidity
Unfortunately, the fluid needs due to these conditions varies. Use your best judgment based on your energy levels and perspiration.
The bottom line with hydration:
Drink non-caffeinated, sugar-free beverages consistently throughout the day. By spreading out your fluid intake, you will increase your body's absorption (you will excrete less of it) and it will be easier to reach the recommended intake.