Why You Don’t Need to Drink 8 Glasses of Water a Day

Maybe it was your mother reminding you or some long-forgotten high school gym teacher, but you’ve probably heard that you need to drink eight glasses of water a day. Some call it the 8×8 rule, meaning eight 8-ounce glasses of water a day. What’s so special about eight and how important is this particular number when it comes to daily water consumption?

Of course, drinking water is essential for good health. After all, mild dehydration can lead to everything, from lack of energy and headaches to impaired concentration, and generally put you in a foul mood.

We’ve been buying into this myth for over 70 years

It’s believed that this eight glasses a day recommendation started back in 1945, when the US Food and Nutrition Board released a report stating that people should consume one ml of water per calorie of food they consumed. (Really? We’re tracking our water intake down to the calorie?)


They recommended that for an average 2,000 calorie-a-day diet, 2,000 ml (which equates to roughly 64 ounces), was needed. Thus, it was suggested that to get those 64 ounces of water, a person should drink eight 8-ounce glasses. What you might not realize is that the report said it was also possible to get those 64 ounces of water from the various foods we consume. Now just about all the food we eat has some water in it; however, you’re probably not going to get the hydration you need from eating a basket of deep-fried shrimp. On the flip side, if you’ve ever bitten into a watermelon, then you know just how much water is in those things. Somewhere along the line, that part of the suggestion seems to have been phased out, but the hard 8×8 rule stuck.

This report from 1945 was only cemented into the public’s mind in 1974, when a nutritionist named Dr. Frederick Stare coauthored a book suggesting people drink 6-8 glasses of water daily. Just like in the 1945 report, Stare mentioned that many fruits and veggies have plenty of water to add to that 6-8 glasses a day, but again, people fixated only on the 6 to 8 glasses part.

So how much water SHOULD you drink a day?

The short answer: drink water when you’re thirsty. Mind-blowing, right?

The US National Library of Medicine National Institutes of Health found that there was actually no scientific evidence suggesting eight 8-ounce glasses of water was needed for healthy water intake. Of course, depending on what sort of climate you live in, how much you exercise, or if you have a fever, your body might need more than that, or it might need less.

Our bodies lose water every day, no matter what kind of climate you might live in or how often you exercise. You’re going to lose 500-1,000 ml of water a day even if you’re just sitting on your butt in the Arctic. Our bodies have this amazing ability though to let us know when they need water – it’s called thirst.

It should be noted though, that as reliable as thirst is, it’s not perfect. As we get older, it tends to fade some and older people run a higher risk of being dehydrated. If you’re thirsty, drink some water (or ice tea, or milk, or eat an apple) and if it’s really hot out, maybe drink an extra glass of water.

You’re not likely to drink so much water that it becomes dangerous, unless you have a kidney disease and your body can’t excrete it from the body properly.

The health benefits of drinking water

It probably doesn’t come as a shocker, but drinking water is good for you. It can reduce headaches, aid in weight loss by reducing your appetite, and help with constipation. Some people believe that it can help in flushing toxins from your kidneys, but the research out on this is still fuzzy. We have about five liters of blood inside us at any moment, and our kidneys filter the equivalent of our blood volume 36 times a day. Any excess water consumed isn’t doing much extra.

The takeaway here is that yes, drinking water is healthy for you, but there’s no magic health reward for guzzling eight glasses of H2O every day. Just drink whenever you’re thirsty, and you’ll be fine.


Photo credits: Giphy, Hill Laboratories, Dailyvoice.co.za, NZ Herald, Advanced Water Solutions

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