Hint: Probably more than you're currently drinking. 

By Maggie O'Neill
August 27, 2019

Drinking water is kind of non-negotiable when it comes to, you know, living. But while we all pretty much know we have to drink water to keep our bodies functioning, we can't seem to agree on just how much water we need.

The truth? Water intake isn't exactly a one-size fits all prescription. Instead, how much water you need to drink each day is dependent on a bunch of different factors: your weight, how your metabolism works, how much food you eat (and what you eat), what your body temperature is, and how active you are, among other things, according to Baruch Fertel, MD, an emergency medicine physician at Cleveland Clinic.

So what's the deal? How much water should you really be drinking each day—and how do you know if you're hydrated enough? Here's what experts have to say about your sipping habits (or lack thereof). 

Okay, how much water do you officially need each day?

So, the "8 x 8" rule—drinking eight 8-ounce glasses of water a day—is pretty solid advice as a starting point, says Cynthia Sass, RD, Health contributing editor. But "you need to consume more fluid if you’re losing more, through exercise or from being in hot, humid weather," Sass explains. "You may also need more if you’ve been ill and have a fever, are sweating, or are experiencing vomiting and diarrhea."

The Institute of Medicine of the National Academies takes it a step further and suggests women consume an average of 2.7 liters (about 11 cups) of water each day. Note, however, the institute says "consume"—that's because you can get your water intake from both beverages and food. "We don't offer any rule of thumb based on how many glasses of water people should drink each day because our hydration needs can be met through a variety of sources in addition to drinking water," Lawrence Appel, director of the Welch Center for Prevention, Epidemiology and Clinical Research at Johns Hopkins University, said in a press release for the institute. 

As far as those different sources of water go, the institute says "people also get water from juice, milk, coffee, tea, soda, fruits, vegetables, and other foods and beverages as well." Dr. Fertel explains, however, that "not all liquids are created equal." Alcohol, for example, is a diuretic—that means it can have a "paradoxical effect" and cause water loss, says Dr. Fertel. Liquids that contain salts and electrolytes, however (think: sports drinks) can help you retain fluid and hydrate better.

One beverage that doctors and nutritionists are on the fence about, though? Coffee. In the past, your fave cup of Joe was thought to be dehydrating, but Sass says that the caffeinated beverage actually can hydrate you, depending on how you consume it. "Newer research shows that our bodies can adjust to caffeine, which negates its diuretic effect—as long as [intake is] consistent and not excessive. On the other hand, if your caffeine intake is erratic, you may experience a diuretic effect.”

RELATED: What Causes Dehydration? Here’s What You Need to Know

How can you tell if you're drinking enough water?

Take a look in the toilet—no, really. Dr. Fertel says that the color of your pee can tell you a ton about your drinking habits. "Urine should be the color of lemonade: a touch of yellow." If you're peeing infrequently and your urine looks bright or dark yellow, that could be a warning sign that you're not getting enough H2O.

Additionally, confusion, the inability to drink liquids, and severe weakness are signs of dehydration. If you experience any of these, or if you have no urine output, you should seek medical attention, according to Dr. Fertel. And definitely don't let your thirst guide you: "By the time you feel thirsty you're already slightly dehydrated," says Sass. (Though, to be clear: You should always drink when you're thirsty—but the best route is to drink before you feel thirsty.)

Something else to keep in mind: Dehydration isn't something to be taken lightly. One myth about water intake, says Sass, is that dehydration is no big deal, but "just a 2% loss of body fluid can negatively impact physical performance, and a 1-3% loss has been shown to impair mood, reduce concentration, increase headaches, impair working memory, and increase anxiety and fatigue," Sass says.

Basically, staying hydrated is important—but there's no quick answer to exactly how much water your body needs each day. Your best bet? Starting off with the "8 x 8" rule and then paying attention to your body from there and supplementing with a few more glasses when needed. 

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