Water, water everywhere: How much should you drink?

I have always extolled the health benefits of drinking pure, unpolluted water. Remaining properly hydrated is vital to being optimally well. Dehydration, or lack of proper water in the body, can lead to dozens of ailments and pains and even disease.

Over the years, I’ve written a handful of articles on the effects of water on health, and I have read hundreds more. Yet last week my email inbox was flooded with no fewer than 10 articles claiming to tell me everything I know about water is wrong.

In fact, these emails argued, it is the bottled-water industry that tries to make us believe drinking eight 8-ounce glasses of water per day is necessary for health.

“We may not be as dehydrated as bottled-water makers would have us believe,” reported Betsy McKay in The Wall Street Journal. McKay’s comment was in response to a peer-review study that “found no evidence to support the vigorously promoted assertion that drinking at least eight 8-ounce glasses of water a day (known as the “8×8″ rule) is essential to good health.”

Water Rules

In questioning the origin and necessity of the 8×8 water rule, the American Journal of Physiology asked Heinz Valtin, M.D., to undertake a rigorous literature review to ascertain the scientific proof for the daily drinking of 64 ounces of water. Valtin was the go-to physiologist for this project, as he has been active in the field for decades and has written several textbooks on the kidneys and water balance.

After undertaking nearly a year surveying the scientific literature with the help of Dartmouth biomedical librarian, Sheila Gorman, Valtin said his findings were surprising. According to the evidence, he said, the need to drink eight 8-ounce glasses of water per day is unfounded. In other words, it lacks scientific support.

In response to this, Valtin pondered how it would otherwise be “difficult to believe that evolution left us with a chronic water deficit that needs to be compensated by forcing a high fluid intake.”

Professor Valtin is not saying don’t drink water. He is saying that 64 ounces per day is not a scientific absolute for most people. And given that most Americans are sedentary and are not exercising or in labor-intensive jobs where they sweat a great deal, perhaps he is correct. Here’s the rub, for me. In one of the many email newsletters I received on the subject, one of the doctors said this study is proof that we don’t need to drink water. What’s more, he said he has not had a glass of water in more than 10 years.

How can a trained doctor say and do such nonsense, I wondered? Well, he supported his notion by claiming that we get enough water from the food we eat and from other beverages we consume, like — wait for it — beer, coffee and soda. On this point, he and Valtin agree. On this point, I get angry.

Life Depends On Water

If you want to use science as the basis for claims, then use the very foundation of science that points to how life comes about: water. In our search for proof of life (or potential life) on other planets, scientists get excited when they find old ravines or ice on planets. Why? Because water is essential to life! No living organism can survive without water. And not only a little bit of water. Ample water.

The Earth is mostly water. Where there is water, lush vegetation and people thrive. Where there is no water, desert and death prevail. The human body is roughly 60 percent water, and the brain is more than 70 percent water. Dehydration in the body is akin to creating an interior desert environment, wherein cells and tissue start to break down and die. Water is essential to wellness. Period.

If we use the above-stated food and beverage argument for water consumption, we need to look at the facts of it. According to its research, the Mayo Clinic states that, on average, the food we eat contributes to only about 20 percent of our daily water intake. That leaves the other 80 percent to be consumed through beverages like water, soda, coffee, beer, fruit juice, etc. However, beer, coffee, soda and juice are diuretics and cause us to lose water. So their consumption is counterproductive in helping us hit the daily water quota we need to be healthy.

Moist And Healthy

Why do we need water to be healthy? Simply because it keeps our organs moist and healthy, helps move toxins out of the body and carries nutrients to our cells. When we don’t have enough water to do this, we begin experiencing negative (ill-health) effects like dry skin, constipation, headaches, fatigue, joint pain and allergies, among other issues. (I’d be curious to know if the doctor who said he had not drunk a single glass of water in a decade has any of these health concerns.)

OK, so this particular take on the study may not be in line with the full story of the study. So to get back to Valtin’s conclusion: “I have found no scientific proof that absolutely every person must ‘drink at least eight glasses of water a day.'” He also noted that the studies have been limited to somewhat sedentary adults who reside in temperate climates. Those two points are my biggest takeaway from the Dartmouth study.

If you want to be healthy, you must exercise and you must sleep. Both activities cause you to lose water through sweat. You also lose water through respiration, digestion, urination and bowel movements. What’s more, if you drink coffee, black tea, soda, alcohol or beer, or eat spicy food or take certain prescription medications, you are causing an ongoing diuretic effect and losing even more water as a result. Therefore, you need to drink more water to remain hydrated.

I agree with Professor Valtin that the 8×8 rule is not for everyone. Maybe it’s not even for anyone. However, I don’t agree that we get enough water in the food and non-water beverages we consume. I see vast changes in wellness in my patients when they change their diets and replace diuretic beverages with water. Moreover, I think the limit of this study to sedentary adults in moderate climates tells a lot about the limitation to applying its conclusion. If you live in a warmer or dryer climate, and if you are active through work or exercise, then you certainly need to replenish larger quantities of lost fluids.

In the end, to be a healthy human, one must be roughly 60 percent water. When we’re low on our level, we experience the effects of ill health. While you may not need 64 ounces per day, you still need to remain hydrated. And drinking pure water is the way to do this.


  1. Water: How much should you drink every day? — Mayo Clinic
  2. 8×8 study prompts a deluge in the press (as well as in puns) — Dartmouth Medicine
  3. “Drink At Least 8 Glasses Of Water A Day” — Really? — Dartmouth Medical School


Dr. Mark Wiley

By Dr. Mark Wiley

Dr. Mark Wiley is an internationally renowned mind-body health practitioner, author, motivational speaker and teacher. He holds doctorates in both Oriental and alternative medicine, has done research in eight countries and has developed a model of health and wellness grounded in a self-directed, self-cure approach. Dr. Wiley has written 14 books and more than 500 articles. He serves on the Health Advisory Boards of several wellness centers and associations while focusing his attention on helping people achieve healthy and balanced lives through his work with Easy Health Options® and his company, Tambuli Media.