NSF
NSF International, The Public Health and Safety Company, a not-for-profit, non-governmental organization is the world leader in developing national standards and product certification.
NSF is the leading independent tester of home water treatment 
equipment, evaluating hundreds of brands of water treatment devices each year to ensure they meet the design and performance requirements of national public health standards.
Consumers can be confident that home water treatment devices that carry NSF certification will actually reduce the contaminants as claimed by the manufacturer on the product label.
NSF Mark featured on CBS Early Show
NSF's Drinking Water Treatment Units Laboratory - video
NSF's Drinking Water Site - comprehensive consumer guide