Contribution of tap water to mineral intakes of Canadian preschool children.

Tap water consumption was estimated from 3 day weighed dietary records in 102 Canadian preschool children (4-5 yr of age; 58 males, 44 females). Cold tap water samples were also collected from each child's household (64 hard water households, 38 soft water households) and analyzed for calcium, magnesium, sodium, zinc, copper, and sodium by atomic absorption spectrophotometry. Median consumption of tap water consumed alone and tapwater alone plus that used in beverages (ml per day) was 36.5 (range 0-791) and 171.5 (range 0-1036), respectively. Average intakes of macrominerals for males (M) and females (F) from all sources of hard tap water were (mg/day): calcium (M) 16.5, (F) 13.2; magnesium (M) 6.6, (F) 4.5; and sodium (M) 2.3, (F) 2.3. Average intakes of macrominerals from soft water are as follows: calcium (M) 0.1, (F) 0.1; magnesium (M) 0, (F) 0; and sodium (M) 31.0, (F) 24.4. Trace element intakes from tap water were negligible. Hard tap water provided less than 8% of the Canadian Recommended Nutrient Intake (RNI) for magnesium, less than 3% for calcium, and less than 1% for zinc. Mineral contributions of soft tap water to the RNIs were less than 2%.