A significant source of many toxic elements to which individuals are exposed may be in drinking water. There are serious health problems associated with naturally elevated arsenic levels in drinking water in different parts of the world. Lead is another potentially serious drinking water problem as lead can be introduced into drinking water by old pipes in homes or by old plumbing systems bringing water to houses. Additional metals regulated by the EPA include aluminum, antimony, barium, beryllium, cadmium, chromium, copper, iron, manganese, mercury, nickel, selenium, thallium, uranium and zinc. Fluoride is a controversial element which can adversely affect health at relatively low concentrations. pH is an important parameter to check because acidic water may cause corrosion in water pipes and leach metals such as lead and copper into the water you drink. To assure safe drinking water, you should test your water for these elements.