“No, You Do Not Have to Drink 8 Glasses of Water a Day,” The New York Times recently proclaimed. That is absolutely correct; there is no science behind that recommendation, as many journal articles have pointed out over the last decade.
So, where did the myth stem from and why does it refuse to go away?
“Many people believe that the source of this myth was a 1945 Food and Nutrition Board recommendation that said people need about 2.5 liters of water a day. But they ignored the sentence that followed closely behind. It read, “Most of this quantity is contained in prepared foods,” Aaron Carroll — professor of pediatrics at Indiana University School of Medicine — explains in the NYT article.
It appears that industry funding has played a significant role in keeping the 8-glasses-a-day myth alive:
“A 2012 study in the Annals of Nutrition and Metabolism used it to declare that almost two-thirds of French children weren’t getting enough water. Another in the journal Public Health Nutrition used it to declare that almost two-thirds of children in Los Angeles and New York City weren’t getting enough water. The first study was funded by Nestlé Waters; the second by Nestec, a Nestlé subsidiary.”
P.S.: Here is another study on water intake funded by Nestlé that we found.