In one such study on this myth, done in 2002, Heinz Valtin, a Dartmouth Medical School physician and kidney specialist,
who researched the subject thoroughly, released his findings.
Valtin found that,
among most adults, caffeinated and alcoholic beverages constitute half or slightly more of their daily fluid intake, meaning the average adult drinks a respectable 1,700 ml and this doesn't include the water from foods and metabolism, which also count.
Valtin thinks the notion may have started 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 two to two-and-a-half quarts per day(64 to 80 ounces).