It’s common knowledge that we should drink at least eight glasses of water a day. Or at least many people think it’s common knowledge.
Heinz Valtin, a Dartmouth Medical School physician, disagrees.
In an invited review published by the American Journal of Physiology, Valtin reported that there is no supporting evidence to back up the popular recommendation to drink eight 8 oz. glasses of water per day.
How did the 8 X 8 myth start? Valtin thinks that the notion may have started in 1945 when the Food and Nutrition Board of the National Research Council recommended approximately “1 milliliter of water for each calorie of food,” which would amount to roughly 2 to 2.5 quarts per day (64 to 80 ounces).
In its next sentence the board stated, “[M]ost of this quantity is contained in prepared foods.” But that last sentence seems to have been missed, so that the recommendation was erroneously interpreted as how much water a person should drink each day.