Most people (including doctors) say and also newspapers states that an average person should drink 2 litres (approximately 8 glasses) of water per day.

Even though this is very popular I have heard about this many times, I have never actually heard about the person who discovered this number and the history related to this.

And I don't know what these scientists exactly took into account when calculating this. I think this came from measuring how much water your body needs and the calculations said that 2 litres is the correct amount.

So therefore Im asking this over here.

Who was the scientist/group of scientists, and when and how did he find this number.

  • 2
    $\begingroup$ Obviously, "8 glasses" is not the essential content of the statement. The point is that a human should consume approximately X (2 liters?) amount of water a day: One could ask about this in a more direct and to-the-point fashion, without referring to the "8 glasses" stuff at all, and this would significantly improve the question. $\endgroup$
    – Danu
    Commented Nov 15, 2014 at 17:01
  • $\begingroup$ @Danu Done :))) $\endgroup$
    – The Artist
    Commented Nov 16, 2014 at 2:41

1 Answer 1


This article in Slate, Who Says You Need Eight Glasses a Day?, traces the history of this idea. Quick summary:

[T]he [Slate] Explainer has uncovered evidence of the 8x8 myth going all the way back to 1796, in a German text by Dr. Christoph Wilhelm Hufeland called Makrobiotik. The book includes an anecdote about the surgeon general to the king of Prussia, a vibrant 80-year-old man who had "contracted the habit of drinking daily from seven to eight glasses" of cold water and thus "enjoyed much better health than in his youth."

The article goes on to relate the history of the hydrotherapy craze. It also mentions the most commonly cited source, the 1945 recommendations of the Food and Nutrition Board of the National Research Council (a U.S. organization), which wrote:

A suitable allowance of water for adults is 2.5 liters daily in most instances. An ordinary standard for diverse persons is 1 millimeter for each calorie of food. Most of this quantity is contained in prepared foods.

This last sentence seems to have been ignored in the "drink 8 glasses of water a day" advice.

  • $\begingroup$ I can't find anything better than what you have here (nice answer, +1), but if you want to add more about the US government's report, you might find this helpful. There's not enough for me to post an answer. $\endgroup$
    – HDE 226868
    Commented Nov 16, 2014 at 1:57
  • $\begingroup$ @TheArtist accepted answer if you feel it is good answer. BTW +1 :) $\endgroup$
    – Freddy
    Commented Nov 16, 2014 at 6:27

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