NSF P473: Retired PFOA/PFOS protocol
Official title: NSF Protocol P473 (PFOA and PFOS reduction), retired
A former NSF test protocol for PFOA and PFOS reduction. NSF moved its claims into NSF/ANSI 53 and 58 and removed all products and references to P473.
What it can cover
- Nothing today. PFOA and PFOS reduction claims now sit under NSF/ANSI 53, and under 58 on some listings.
What it does not
- Any current certification. NSF's listing search returned no P473 products on Oct. 4, 2026.
- PFAS other than PFOA and PFOS
The usual mistake
Calling it "NSF/ANSI 473" and treating it as a live PFAS standard. NSF calls it Protocol P473, and its claims were folded into NSF/ANSI 53 and 58.
The fine print
- NSF built P473 after EPA's 2016 health advisory of 70 ppt for PFOA and PFOS combined.
- In 2017 an NSF task group began moving it into 53, for carbon and anion exchange devices, and 58, for RO systems.
- NSF's 2022 updates added a Total PFAS claim and lowered the combined limit from 70 ppt to 20 ppt.
- The NSF pages checked do not describe any American National Standard numbered 473, and P473's full official title could not be confirmed on a live NSF page.
Sources
- Forever Chemicals and the Advancement of Filtration Standards, NSF. Checked Oct. 4, 2026.
- PFAS in Drinking Water, NSF. Checked Oct. 4, 2026.
- Search for NSF Certified Drinking Water Treatment Units (standards and reduction claims lists), NSF. Checked Oct. 4, 2026.
Where to go next
Filters, checked
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