More contaminants are being introduced into municipal drinking water supplies from landfills (trash dumps), industrial pollutants and agricultural run-off. The four-stage filter system from Vertex Water Products, of Montclair, Calif., uses advanced reverse osmosis membrane technology to remove dissolved molecular contaminants from tap water. This is the same technology used by most bottled water companies. All filter elements are made in the U.S. and NSF approved—assuring a high quality filter system.