How Much Water Should You Drink Daily?

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My whole adult life I’ve been told I don’t drink enough water daily. Like most people, I have an idea of how much water I should be drinking. So I decided to see what my research would find.

What health organisations say

If you ask any adult how many 8-ounce glasses of water they’re supposed to drink daily, they’ll probably say 8. This is from research carried out in 1945 by the U.S. Food and Nutrition Board of the National Research Council, which recommended this for water intake. Although part of a more complex equation, the recommendation translated to about 64 ounces daily.

In the U.S., the general guidelines by The U.S. National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is about 15.5 cups (about 3.7L) of fluids a day for men and about 11.5 cups (about 2.7L) of fluids a day for women.[1] Organizations like the Mayo Clinic and Harvard Medical School also agree upon this information.

Others like The Institute Of Medicine, The National Academies Press, The National Academy of Medicine, AARP, Harvard T.H.Chan and Health suggest 13 cups (about 3L) for men and 9 cups (about 2L) for women.

The University of Missouri System suggests a different formula: your mass ÷ 2 = number of ounces of water per day. So, if you weigh 200lbs, then 200 ÷ 2 = 100 oz water per day.

Can we get away with less?

Now, even more interesting (or confusing), in Australia the Better Health Channel recommends 10 cups (about 2.6L) for men and 8 cups (about 2.1L) for women. [2]

The European Food Safety Authority recommends 10.5 cups (about 2.5L) for men and 8.5 cups (about 2L) for women. In the U.K., The Eatwell Guide for the NHS recommends that people drink 6 to 8 cups (about 1.4L–1.9L) or glasses of fluid a day. [3]

It has to be pointed out that fluids don’t only refer to water. About 20% of daily fluid intake usually comes from food and the rest from drinks. Drinks also mean most drinks, although all the research, quite rightly, says to try and avoid sugary drinks.

Water percentages of food

Here is an interesting table with some food items and their water percentage: [4]

Percentage	Food item
100%	Water
90–99%	Fat-free milk, cantaloupe, strawberries, watermelon, lettuce, cabbage, celery, spinach, pickles, squash (cooked)
80–89%	Fruit juice, yogurt, apples, grapes, oranges, carrots, broccoli (cooked), pears, pineapple
70–79%	Bananas, avocados, cottage cheese, ricotta cheese, potato (baked), corn (cooked), shrimp
60–69%	Pasta, legumes, salmon, ice cream, chicken breast
50–59%	Ground beef, hot dogs, feta cheese, tenderloin steak (cooked)
40–49%	Pizza
30–39%	Cheddar cheese, bagels, bread
20–29%	Pepperoni sausage, cake, biscuits
10–19%	Butter, margarine, raisins
>1–9%	Walnuts, peanuts (dry roasted), chocolate chip cookies, crackers, cereals, pretzels, taco shells, peanut butter
0%	Oils, sugars