Drinking Water Can Be a Significant Source of Dietary Calcium

The half gallon of water you should be drinking daily may have 1/4 or more of your dietary calcium requirement.


My local water department (Town of Gilbert, Arizona) told me today that my water currently has 55 mg/l of calcium, and typically varies from 40-70 mg/l of calcium. That's about 100 mg per day from 1/2 gallon of water, or around 1/10 of the daily requirement. If I add in the water I use for cooking (1 quart for each meal), my tap water is giving me at least 1/4 of my calcium needs.

Sources:

1.
http://www.mgwater.com/hankin.shtml

"A pilot study among forty-five adult volunteers living in a hard-water community of California was conducted to determine the contribution of water to total calcium and magnesium intakes. A food composition table was compiled and local water supplies were analyzed for calculating seven-day calcium and magnesium intakes. The contribution of water to the total mineral intakes averaged 7 per cent for calcium and 12 per cent for magnesium. The magnesium contributions were probably overestimated due to lack of nutrient data for several reported foods.
"The frequent use of water softeners and the mobility of the subjects decreased the expected contributions of hard water to total calcium and magnesium intakes. Further studies on the possible relationship of water constituents to cardiovascular diseases will depend on the identification of a population that consumes primarily hard, untreated water and on the availability of additional information concerning the content of foods."
2.
http://goaskalice.columbia.edu/calcium-hard-water
"80 to 120 milligrams of calcium per liter of water"
3.
http://en.wikipedia.org/wiki/Hard_water
"More than 85% of American homes have hard water.^[42] The softest waters occur in parts of the New England, South Atlantic-Gulf, Pacific Northwest, and Hawaii regions. Moderately hard waters are common in many of the rivers of the Tennessee, Great Lakes, and Alaska regions. Hard and very hard waters are found in some of the streams in most of the regions throughout the country. The hardest waters (greater than 1,000 ppm) are in streams in Texas, New Mexico, Kansas, Arizona, and southern California.^[43]"

4.
Town of Gilbert Water Department phone conversation with Tom Haws 2012-03-19.