Does Tea Dehydrate You? How It Compares To Water & Coffee

Tea is a popular beverage around the world, beloved for both its soothing taste and the many impressive health benefits that it has to offer. However, because of its caffeine content, many may wonder whether tea helps or hinders hydration.

"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.

The idea that tea can cause dehydration stems from its caffeine content, as studies show that drinking large amounts of caffeine—around 250 to 300 milligrams, or between five and eight cups of tea—could act as a natural diuretic7 and throw off fluid balance.

However, Ruxton points out that these studies are based on the consumption of high-dose caffeine pills rather than caffeinated drinks. In fact, studies on the effects of caffeine-containing beverages like coffee have actually found that it offers pretty similar hydrating properties8 as water when enjoyed in moderation.

According to Cohen, if you're drinking less than eight cups of tea per day, it's unlikely to cause dehydration. Ruxton agrees, explaining that "tea will never cause dehydration because the modest caffeine content of 40 to 50 milligrams per serving is always teamed up with 100 to 250 milliliters of water."

While tea can help keep you hydrated, going overboard may do more harm than good when it comes to your health, which is partially due to its caffeine content.

"The European Food Safety Authority recommends that we keep our daily caffeine intake below 500 milligrams per day, which equates to around 10 cups of tea," says Ruxton. Exceeding this amount can cause a slew of side effects, including anxiety, dizziness, headaches, and insomnia.

Because of its caffeine content, it's also best to stick to drinking caffeinated tea earlier in the day to avoid interfering with your sleep schedule. Drinking a cup right before bedtime can also increase the risk of waking up in the middle of the night for a bathroom break.

So, does tea dehydrate you? According to the experts, it can actually be just as hydrating as water, so long as you don't go overboard. In fact, Cohen points out that caffeine-free varieties like herbal tea can be a flavorful way to meet your daily fluid requirements, especially if you don't like the taste of plain water.