This urban myth does not seem to hold water

The 8X8 theory (to be healthy, drink at least 8 glasses of water per day) is hogwash. That is the verdict reached in an editorial that reviewed some of the fallacies and facts behind this popular advice doled out by docs and non-docs as a first step to keeping healthy. Article here at the Journal of the American Society for Nephrology.

It is widely known that humans cannot survive for more than a few days without ingesting water in excess of solutes. The dangers of severe hypertonicity and volume depletion are not up for debate. It is also obvious that individuals in hot, dry climates have increased need for water, as do people who engage in strenuous physical exertion. There are certainly well-recognized disease states, such as nephrolithiasis, for which increased fluid intake is therapeutic, but do average, healthy individuals living in a temperate climate need to drink extra fluid—even when not thirsty—to maintain health? The classic recommendation is known as “8 X 8”: Eight glasses of 8 oz of liquid per day—not including caffeinated and alcoholic beverages. Where did this recommendation come from?