Think You Need 8 Glasses of Water a Day? Scientists Say the Real Answer Is Much Simpler

The age-old advice to drink eight cups of water a day? It may just be nothing more than a myth.

According to a major study published in the peer-reviewed journal Science, drinking eight cups of water a day is unnecessary for most healthy adults.

The advice is misinformed primarily because of what it omits; it does not take into account the water received from other sources, like tea or cucumbers.

The findings suggest that an individual’s water needs vary and depend on factors such as their age, size, physical activity levels, and climate.

The scientists behind the study said that for healthy adults, there is no real need or benefit to drinking eight cups of water a day. However, they added that it is not necessarily dangerous to do so: Your body will just excrete the extra water through urine.

How much water do you actually need?

“Hydration is highly individual. There isn’t a single amount that works for everyone, or even for each person each day, because fluid needs vary based on body size, fitness, activity level, environment, sweat rate, and heat acclimatization status,” Rebecca Stearns, PhD, the chief operating officer of the Korey Stringer Institute at the University of Connecticut told Inc.

Herman Pontzer, PhD, is a professor of evolutionary anthropology at Duke University. He agrees with Stearns, telling Inc. that “the best way to personalize your hydration is to listen to your body. If you’re thirsty, drink.”