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ganic compounds, as well as by varying intakes of electrolytes, must be accommodated by adequate total water consumption. Hence there is no single daily total water requirement for a given person, and need varies markedly depending primarily on physical activity and climate, but also based on diet. It would be misinterpreting the basis for setting the AI to state that there is a“requirement” for water at the level of the AI. As is discussed in Chapter 1, the AI does not represent a requirement; it is an amount that should meet the needs of almost everyone in the specific life stage group under the conditions described. It is thus determined on a different scientific basis than other recommendations for water or fluid intake (NRC, 1989).

The AI for total water intake for young men and women (19 to 30 years) is 3.7 L (131 oz) and 2.7 L (95 oz)/day, respectively, which correspond to median intakes for this age group in the NHANES III survey (Appendix Table D-1). Fluids (drinking water and beverages) provided about 3.0 and 2.2 L/day for 19- to 30-year-old men and women, respectively, representing approximately 81 percent of total water intake (Appendix Table D-3). Water from food provided 19 percent of total water intake, or 0.7 L/day for men and 0.5 L/day for women (Appendix Table D-4). While it is recognized that the median intake for men and women 31 to 50 years was lower, there is no reason to assume that the level recommended for adults 19 to 30 years would be in excess. Therefore, the AI for those ages 31 to 50 years is set equal to that for younger adults.

It is recognized that nationwide surveys such as NHANES III that rely on self-report are often inaccurate and possibly biased, with a greater tendency to underestimate actual intake (IOM, 2001b). People who meet the recommended 60 minutes per day or the equivalent of moderate physical activity (IOM, 2002/2005) and consume approximately 2,200 kcal can meet the AI through beverages and food (see Table 4-14).

Total Water AI Summary, Ages 19 Through 50 years

AI for Men

19–30 years

3.7 L/day of total water. This includes approximately 3.0 L (13 cups) as total beverages, including drinking water.6

31–50 years

3.7 L/day of total water. This includes approximately 3.0 L (13 cups) as total beverages, including drinking water.


Conversion factors: 1 L = 33.8 fluid oz; 1 L = 1.06 qt; 1 cup = 8 fluid oz.

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