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Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate
the minimal, average, and liberal water requirements approximated 2.1, 3.4, and 5.0 L/day, respectively. In addition, Adolph (1933) concluded that a convenient “liberal standard” for total water intake is 1 mL/kcal expended. Subsequent studies by Johnson (1964) recommended minimum daily water requirements of no less then 0.91 L for survival conditions and 3.0 L for hot weather.
Table 4-5 presents water balance studies that have estimated daily total water requirements for adults. These requirements are above minimal levels because some physical activity (although usually nominal) was allowed and because individuals self-selected the volume of consumed fluids (i.e., ad libitum water consumption). For the prolonged bed-rest studies, greater emphasis was placed on data obtained during the initial week, if available. Water balance studies suggest that the required water intake to maintain water balance for resting adult men is approximately 2.5 L/day (Adolph, 1933; Newburgh et al., 1930). If modest physical activity is performed, the
TABLE 4-5 Estimation of Daily Water Requirements of Adults from Water Balance Studies
Total Water Intake (L/d)
Yokozawa et al., 1993
Newburgh et al., 1930
Repeated studies of men
Temperate, rest, variety of diets
Welch et al., 1958
Active, ambient temperature range of −30°C to +30°C
≈ 3.0 at −20°C to +20°C
≈ 6.0 at +30°C
Consolazio et al., 1967
Temperate, rest, starvation study
≈ 2.5 (1st 4 d; ~ 3.4 if corrected for negative balance)