This scientific symposium target the epidemiology, dietary intake, biochemistry and health effects of magnesium and calcium as well as the practical concerns (treatment technology and costs) associated with their addition to drinking water. The symposium will review possible health significance of magnesium and calcium in drinking water and help to define what questions need to be resolved before a decision can be made on the value of a water contribution of magnesium and calcium to total diet and what studies are necessary to do so.