Calcium from hard water?

Dear Alice,

Is it bad for you to drink hard water? Can the calcium in hard water be absorbed by your body and would this be good for you, like the calcium in milk?

Dear Reader,

Water is designated as "hard" when it contains a high concentration of dissolved minerals, such as calcium and magnesium. There is a long-standing debate on the effects of consuming hard water and heart disease. Some scientists claim that hard water can help prevent or lower the risk of heart attacks, while others argue that it can actually increase the prevalence of cardiovascular disease, and still others say that there is no correlation between the two at all. What we do know is that your body does absorb the calcium in hard water, and utilizes it the same way it would if it came from any other food source. Besides building and strengthening your bones and teeth, calcium is also used in conducting nerve impulses and muscle contractions throughout the body.

There are many other factors that affect the amount of calcium your body actually absorbs from what you eat and drink. The presence of small to moderate amounts of fat are necessary when consuming vitamins A and D to increase absorption rates. Milk, other than skim milk, provides the necessary fat to absorb these vitamins. The sugar found in milk, lactose, also helps your body absorb calcium. This is why milk is so well known for being an excellent source of calcium, since it is also fortified with vitamins A and D. An 8-ounce glass of milk provides about 300 milligrams out of the 1000 milligrams of calcium recommended daily for those between the ages of 19 and 50. For those between the ages of 9 and 18, the requirement goes up to 1,300 milligrams a day because the body is growing so rapidly.

Hard water does contain calcium, but significantly less than milk; 80 to 120 milligrams of calcium per liter of water (or about 20 to 30 milligrams per 8 ounces. So you may not want to give up the milk just yet, unless you are also eating large amounts of calcium-rich foods (cheese, yogurt, broccoli, etc). Nevertheless, drinking hard water can contribute a small portion of calcium to your diet.

Since the hardness of water varies from community to community, you could find out the exact levels of calcium in the tap water from local water treatment and delivery authorities. After doing that, you can decide for yourself whether you want to milk your hard water for all it's worth!

Last updated May 19, 2015
Originally published Mar 21, 2008

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