The One Myth About Drinking Water You Need to Stop Believing

Experts are breaking down whether the "8 glasses a day" rule is actually true.

There are many shared pieces of "health advice" that we hear throughout our lives and take at face value—even if it turns out, they're not completely true. In fact, one of the biggest misconstrued pieces of advice is that everyone should be drinking 8 glasses of water daily. According to experts, that's not accurate. Instead, how many glasses of water you should drink every day depends on a number of factors, including your age, gender, and weight. Read on to find out how much you should really be drinking, and for more things you believed about your health that aren't actually true, discover The Biggest Myth About Blood Pressure You Need to Stop Believing.

The average healthy person should drink around 4 to 6 glasses of water every day.

young beautiful woman by the window at home drinking water. Lifestyle

Experts from the Harvard Medical School say that "most people need about four to six cups of water each day." But they note that this calculation is for "generally healthy people," so the actual amount can fluctuate by a lot depending on each individual person.

Andrea Paul, MD, a medical advisor and founder of Health Media Experts, says drinking enough water is important for good body health, especially when it comes to taking care of the kidneys, which filter blood and maintain water balance. So while 8 glasses every day may not be necessary for everyone, this assumption is based on "water's physiological importance for the human body," which means it's not necessarily a harmful myth. And for more health help, find out How Often You Should Really Be Changing Your Sheets.

But exactly how much you should drink depends on a multitude of factors.

Woman stepping on scale to check weight

Shena Jaramillo, MS, a registered dietitian nutritionist, says there are many factors that can change your necessary water intake. This includes age, gender, BMI, physical activity level, illness, the temperature, and even caloric intake and food choices. For instance, Heathline says you'll most likely need more water if you live in humid areas, drink a lot of caffeinated beverages, exercise more, or are losing fluids through a sickness. And for more ways to live a healthy life, learn The Single Best Thing You Can Do for Your Health Right Now.

The myth of 8 glasses a day came from the idea that you can't get water from other means.

Senior man drink mineral water in gym fitness center after exercise. Elderly healthy lifestyle.

According to David Belk, MD, a doctor of internal medicine based in California, a nutritional study from the 1940s concluded that the average person should consume about 2 liters of water every day—which is about 8 glasses. However, he says this finding was misconstrued because people only took away part of the study's information. He says the study also noted that most of the necessary 2 liters of water per day wouldn't actually need to come from a straight "glass of water," but instead may be found in the food we eat.

"Almost everything we eat contains water—except for foods like dry cereal or beef jerky—so our need for water in excess of the food we eat is often minimal," Belk explains. "Drink water when you're thirsty, especially when it's hot or when you are very active. Just drinking water to satisfy some minimum goal is unlikely to benefit you in any way." And for more useful content delivered straight to your inbox, sign up for our daily newsletter.

Though the truth is that most people are dehydrated more often than not.

sweaty man wipes brow after exercise

If you're thinking, "great, I don't need to drink 8 glasses of water every day; I'm doing fine," don't celebrate too early. There is a significant chance that you're still probably not getting as much water as you need every day. According to 2013 study, around 75 percent of Americans may actually be dehydrated.

"Dehydration can impact many aspects of your life," says Barry Gorlitsky, MD, an internal medicine doctor and co-founder of KidneyAide LLC. "Dehydration may lead to lower blood pressures, predisposing to falls, faster heart rates which are linked to higher mortality, and changes in concentration due to brain cell shrinkage as water shifts." And for more ways you could be unhealthy, If You're Pooping This Many Times a Day, You Should See Your Doctor.

And you can tell if you're getting enough water through your urine.


You don't have to wait for a doctor's appointment to find out if you're drinking enough water every day, however. Kim Langdon, MD, OB-GYN for ParentingPod, says that you can use "your urine color to determine relative hydration." The less yellow and more light and clear your urine is, the better your hydration is. And for more ways to know whether you're healthy or not, If You Can Smell This, You're Drinking Too Much Caffeine.

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