What is NSF/ANSI certification for water filters?

The information below relates to common standards referenced in the world of residential water filtration. 

Refrigerator Water Filters and other types of residential water filtration systems/components will typically (but not always) be tested or certified against at least one of these standards.

NSF/ANSI 42: Drinking Water Treatment Units - Aesthetic Effects

NSF/ANSI 42 establishes the minimum requirements for the certification of point of use (POU)/point of entry (POE) filtration systems designed to reduce specific aesthetic or non-health-related contaminants (chlorine, taste, odor and particulates) that may be present in public or private drinking water.

The scope of NSF/ANSI 42 includes material safety, structural integrity and aesthetic, non-health-related contaminant reduction performance claims. The most common technology addressed by this standard is carbon filtration.

NSF/ANSI 53: Drinking Water Treatment Units - Health Effects

NSF/ANSI 53 establishes the minimum requirements for the certification of point of use (POU)/point of entry (POE) filtration systems designed to reduce specific health-related contaminants, such as Cryptosporidium, Giardia, lead, volatile organic chemicals (VOCs) and MTBE (methyl tertiary-butyl ether), that may be present in public or private drinking water.

The scope of NSF/ANSI 53 includes material safety, structural integrity and health-related contaminant reduction performance claims. The most common technology addressed by this standard is carbon filtration.