Some manufacturers of water filters claim their products meet NSF standards, ANSI standards, or both for filtering different contaminants. NSF standards are set by NSF International, while the American National Standards Institute sets ANSI standards. Both these bodies are responsible for setting industry standards for water filtration. Products that claim they meet these standards must effectively filter the listed contaminants. You can feel confident when you purchase products with these claims that the water filters meet industry standards. You may also see other certification seals from organizations including the CSA Group, Water Quality Group, and Underwriters Laboratories. These third-party labs certify water filters to NSF standards for additional peace of mind.