Although conventional wisdom holds that humans need eight, 8-ounce glasses of water each day, the truth is a little more complicated. According to The National Academies of Sciences, Engineering, and Medicine, an adequate daily fluid intake is about 125 ounces (3.7 liters) for men and about 91 ounces (2.7 liters) for women. However, keep in mind that these fluid intake guidelines include all sources of water, not just glasses of the stuff. In fact, we get about 20 percent of our daily water from what we eat, especially fruits and vegetables.
The truth is that when it comes to hydration, one size does not fit all. There are many factors that should influence an individual’s daily water intake, including where you live, your activity level, and your overall health. So while there is no scientific evidence that supports the “8x8 rule,” staying hydrated is still important. The best advice is to trust your own body, and when you’re thirsty, reach for water first.