Dr. Margaret McCartney, a general practitioner from Scotland, says that the common health advice that you should drink six to eight cups of water each day is “thoroughly debunked nonsense”. She argues that it is propagated by bottled water companies out to make a profit.
In a commentary, McCartney quoted experts who say that drinking too much water can cause hyponatremia (low sodium levels in the blood).
According to the Los Angeles Times:
“Experts were quick to pounce on the commentary as being misleading ... The answer isn’t cut and dry, says an article by the Mayo Clinic, and depends on your exercise level, health conditions and the heat and humidity of your environment. In general, the Institute of Medicine recommends about nine cups of beverages for women and 13 cups for men ... Most people do well to drink when they’re thirsty.”