Do you really need to drink 8 glasses of water a day?

This claim, called the '8×8 theory', is based on drinking 8 glasses of 8 ounces (227 mL) of water a day. It was first published in a research report by the Food and Nutrition Administration (FNB) of the American Medical Research Institute in 1945. However, in 2002, Dr. Heinz Baltin of Dartmouth Medical School in the United States published a paper in the Journal of the American Physiology Association.

"After analyzing several papers, we did not find any scientific evidence to support drinking 8 glasses of water a day." Whenever you are thirsty, you can drink water.” Nam-seok Joo, a professor of family medicine at Ajou University Hospital, said, “More than 80% of patients seem to have an obsessive compulsive disorder that requires them to drink a lot of water. Because the amount of water in the body is very thoroughly regulated by the homeostasis mechanism of our body "You don't have to be overly conscious of your water intake," he said. 

Professor Kim Dal-rae of the Sasang Constitution Department at Kyunghee University Dongseo Shin Medical Hospital also said, "If you are an ordinary adult without any health problems, you should adjust the amount of water you drink. You don't have to worry about it in particular," he said. "You can drink water before or after a meal or when you want to drink water."

Isn't wanting to drink water a sign that your body is asking for water? Drinking when you want to drink seems to be the answer.