Two NSF/ANSI standards cover PFAS reduction in home water treatment: Standard 53 for non-RO systems and Standard 58 for reverse osmosis systems. Understanding the difference helps consumers identify correctly certified products for their chosen technology.
NSF/ANSI Standard 53
Standard 53 covers drinking water treatment units that reduce health-related contaminants using technologies other than RO — primarily activated carbon block, GAC, and ion exchange systems. PFAS reduction is among the health effects claims tested under this standard. A pitcher filter, countertop carbon filter, under-sink carbon filter, or whole-house carbon system certified to NSF 53 for PFAS has been independently tested to demonstrate PFAS reduction at specified challenge concentrations and flow rates.
NSF/ANSI Standard 58
Standard 58 specifically governs point-of-use reverse osmosis systems. PFAS reduction testing under Standard 58 challenges RO systems with PFOA and PFOS at standardized inlet concentrations and verifies that the system reduces concentrations to below specified levels throughout the rated filter life. RO certification for PFAS requires testing across the entire filter service interval to confirm performance is maintained as components age.
Matching Certification to Technology
When evaluating a non-RO filter (pitcher, carbon block, under-sink carbon), look for NSF 53 certification specifically listing PFAS or PFOA/PFOS reduction. When evaluating an RO system, look for NSF 58 certification for PFAS. A non-RO product certified only under NSF 42 (taste and odor) has not been tested for PFAS. Verifying the specific contaminant claim — not just the standard number — at the NSF product listings database ensures the certification covers PFAS specifically.