A new analysis has shown the presence of hexavalent chromium, a probable carcinogen, in the tap water of 31 cities across the U.S. Bottled water may not be an alternative, because it is often drawn from municipal water systems and can still contain hexavalent chromium or other contaminants.
Basic water filters do not remove hexavalent chromium. However, reverse-osmosis systems designed for home use can take the chemical out of water.