“Tea is just as hydrating as tap water,” explains Carrie Ruxton, Ph.D., a dietitian for the Tea Advisory Panel and researcher who has studied the effects of tea on hydration.

In fact, a 2011 study conducted by Ruxton compared the hydrating effects of black tea and regular water1 directly. In the study, participants were given six cups of black tea to drink over the course of the day. Their hydration status was measured, and the experiment was then repeated using the same amount of tap water. “The results showed no differences in hydration status,” Ruxton tells mindbodygreen.

This mimics the findings of the Beverage Hydration Index2, which measures how much certain beverages cause the body to retain or lose fluid over four hours when compared to water. Tea comes in right around water, compared to things like coffee, which is slightly (but just slightly) less hydrating thanks in part to its higher caffeine content. Caffeine has a diuretic effect, meaning it can cause you to lose more fluid through urine than you retain.

According to Dana Cohen, M.D., an integrative medicine practitioner and co-author of Quench: Beat Fatigue, Drop Weight, and Heal Your Body Through the New Science of Optimum Hydration, tea can count toward daily fluid intake.

As a general rule of thumb, the Academy of Nutrition and Dietetics3 recommends aiming for at least nine cups of fluid per day for women and 13 cups per day for men. However, they also note that fluid requirements can vary depending on a long list of factors, including your age, sex, activity level, and health status.

Pro tip: Instead of sticking to a specific amount, Cohen recommends drinking enough fluid so that you’re taking a bathroom break every two to three hours to ensure you’re staying well hydrated.