Soft Water, Hard Water

A significantly higher incidence of hypertension and its kin, coronary heart disease, in areas of the country where the water is soft, or lacking in mineral content, has for some time been noticed by the medical profession. But whether it was the hard water that protected the heart or the soft water that harmed it remained an elusive question until Dr. Henry A. Schroeder. Professor Emeritus of Physiology at the Dartmouth Medical School, came up with a plausible theory.

Working out of his laboratory in Brattleboro, Vt., Dr. Schroeder and a high school student assistant, with the aid of a computer, ascertained that coronary dis- ease rates are twice as high in U.S. cities with the softest water, located mainly on the East Coast and in the Pacific Northwest, than they are in cities with the hardest. Checking municipal supplies where the water was softest, they could find no toxic substances to account for the difference. But they also noticed that the softest water was most corrosive.

Dr. Schroeder's conclusion was that soft water absorbs harmful substances such as cadmium, a proven offender in raising blood pressure, through the corrosion of household plumbing, particularly when it has been standing for a considerable time in the pipes. If his theory is born out, the addition of lime to harden community water supplies in soft-water areas or simply running water for a few minutes in the morning before that first drink could mean a substantial reduction in the risk of coronary heart disease.