What Does NSF Certified Mean?

CDC describes NSF International as an independent organization that develops public health standards for products. It says one way to figure out what a water filter removes is to look for an NSF certification on the filter's label, and that you can look up specific products in the NSF database to see what they are certified to remove from water.

The standard number matters. CDC lists Standard 42 for taste and odor, Standard 53 for cyst reduction, Standard 58 for reverse osmosis and Standard 62 for distillation among the NSF standards related to water treatment. The EPA says certification to NSF/ANSI/CAN Standard 61 indicates that a product complies with its lead free requirements for pipes, pipe fittings, plumbing fittings and plumbing fixtures, and that the product has met leachate requirements for contaminants, both metals and non-metals.

The EPA's WaterSense guide says certification of water treatment products helps ensure that manufacturers' claims are independently verified and accurate, and that treatment technologies should be certified to the applicable NSF/ANSI standards for the targeted contaminants. The EPA says its Office of Research and Development participates in the NSF International committees responsible for developing NSF/ANSI/CAN 61.

For regulated noncommunity water treatment in Michigan, the state's environment department says anything that touches the water must be NSF/ANSI certified, with NSF 61 used for treatment system components and media and NSF 53 for health effects, and says these certifications show that the equipment will not leach harmful chemicals into the water.