Kitchen & Cookware
NSF/ANSI water filter standards, and the retired one
A filter is certified for a list of contaminants. Not for water. The list is the product, and one widely cited standard no longer exists.
Last reviewed October 13, 2026 — Selena H.
Water filtration is the one category covered on this site with genuine, contaminant-specific third-party certification — and the one where the certification is most often misread. A filter is never certified to "remove contaminants". It is certified for specific reduction claims, each listed on its performance data sheet, and anything not on that list is not certified.
There is also a trap. NSF Protocol P473, the standard that covered PFOA and PFOS reduction, was retired on 1 June 2021 when those requirements were folded into NSF/ANSI 53 and 58. It is still quoted in marketing and in buying guides years later.
Quick picks
| # | Product | Best for | Material | Price |
|---|---|---|---|---|
| 1 | Brita Pitcher with Elite FilterNSF certified against NSF/ANSI 53 for lead reduction — a specific, verifiable claim. | Certified lead reduction | Plastic pitcher body | |
| 2 | Clearly Filtered Water PitcherPublishes third-party lab results by contaminant. Check which standard each was tested to. | Published lab results | Tritan plastic pitcher with a multi-stage composite filter |
Tap a row to jump to that write-up. Prices are not shown on this site because they change — the button sends you to the live Amazon listing.
What P473 covered, and what replaced it
NSF P473 set criteria for establishing PFOA and PFOS reduction capability for point-of-use activated carbon and reverse osmosis systems. On 1 June 2021 the standards were updated: PFOA and PFOS requirements were added to NSF/ANSI 53 for activated carbon technologies and NSF/ANSI 58 for reverse osmosis, which made P473 redundant. Products and references to it were removed and replaced by 53 or 58.
So if PFAS reduction is why you are buying a filter, the claim to look for is PFOA and PFOS reduction under NSF/ANSI 53 or 58, named on the performance data sheet. A current page still citing P473 as its PFAS credential has not been updated in several years — which tells you something about the page as well as the product.
What each standard covers
| Standard | Technology | Covers | Note |
|---|---|---|---|
| NSF/ANSI 42 | Adsorption and filtration | Aesthetic effects: chlorine taste and odor, particulates | The lowest bar. Nearly every filter holds it |
| NSF/ANSI 53 | Adsorption and filtration, carbon-based | Health effects: lead, cysts, VOCs and more — by specific claim | Now also carries PFOA and PFOS requirements |
| NSF/ANSI 58 | Reverse osmosis | RO system performance, including PFOA and PFOS | Different technology, separate standard |
| NSF/ANSI 401 | Adsorption and filtration | Emerging contaminants: some pharmaceuticals and pesticides | Separate from 53 — a filter can hold one without the other |
| NSF P473 | Retired | Formerly PFOA and PFOS reduction | Folded into 53 and 58 on 1 June 2021 |
The per-claim principle
This is the single most important thing to understand about these standards. Certification under NSF/ANSI 53 is certification for particular contaminants, verified by test. A filter certified under 53 for chlorine taste and odor reduction is not certified for lead, and a filter certified for lead is not certified for arsenic.
The performance data sheet lists exactly which claims are certified, and it is a required document. If a brand makes it hard to find, that is informative. If it says "reduces up to 99% of contaminants", that phrase appears on no certification document anywhere.
Buy for what is actually in your water
- Read your utility's annual water quality report. Published, free, and specific to your supply.
- Consider lead separately if your housing predates 1986, since lead enters from plumbing and solder rather than the source — a clean utility report can coexist with a lead problem at your tap.
- Match the standard to the contaminant. NSF/ANSI 53 with a lead claim for lead; 53 or 58 with PFOA and PFOS claims for PFAS.
- Check who certified it. NSF and WQA both certify to these standards; either is a third-party body.
- Change filters on schedule. Capacity is finite, and past it the filter stops doing the thing it was certified for.
Filters with claims we could verify
Two pitchers, one with a named third-party certification and one that publishes its own lab results.
The picks in full
1. Best for Certified lead reduction
Brita Pitcher with Elite Filter
NSF certified against NSF/ANSI 53 for lead reduction — a specific, verifiable claim.
- Made of
- Plastic pitcher body, activated carbon block filter
- Certified to
- Certified: NSF/ANSI 53 (lead reduction)Third-party certified to NSF/ANSI 53 (lead reduction).
- Certified claims
- NSF/ANSI 42, 53 and 401 claims per the data sheet
- Filter life
- Manufacturer states 6 months
- Body
- Plastic
This is the kind of claim this page is about: a named standard, a named contaminant, and a third-party certification. The filter also carries WQA certification against NSF/ANSI 42, 53 and 401 for the claims on its performance data sheet.
What you give up
The pitcher body is plastic. Certification covers the listed claims only — read the data sheet rather than assuming broader coverage.
Who it's for
Households whose main concern is lead.
Who should skip it
Anyone who wants a glass pitcher.
2. Best for Published lab results
Clearly Filtered Water Pitcher
Publishes third-party lab results by contaminant. Check which standard each was tested to.
- Made of
- Tritan plastic pitcher with a multi-stage composite filter
- Certified to
- Manufacturer claimManufacturer claim; no third-party certification published.
- Claim basis
- Brand publishes third-party lab reports; read the standard tested to
- Flow rate
- Slow by design
- Filter life
- Manufacturer states around 100 gallons
A broader published dataset than most of the category, which is useful when your concern goes beyond lead and chlorine. Read it as what it is: testing the brand commissioned and published, rather than certification carried under a single third-party mark.
What you give up
Slow flow, expensive filters, and "tested to" a standard is a weaker statement than "certified by a body against" it.
Who it's for
People with a specific broader concern who will read the data.
Who should skip it
Anyone who wants one certification mark to rely on.
How we chose, and what we did not do
Every product on this page was checked against its published material composition and its third-party certifications, with each claim labeled as certified, manufacturer-stated or independently tested by a named party. We do not run a lab and we do not claim to have used these products — the full method is here.
Questions people actually ask
What does NSF/ANSI 53 certification mean?
That the filter was tested and certified for specific health-related reduction claims — lead, cysts, VOCs and others — each listed individually on its performance data sheet. It is never a general claim about water quality.
Is NSF P473 still a valid certification?
No. On 1 June 2021 its PFOA and PFOS requirements were folded into NSF/ANSI 53 for carbon systems and NSF/ANSI 58 for reverse osmosis, and P473 was retired. A product or article still citing it is quoting a standard that no longer exists.
Which standard covers PFAS in water filters?
NSF/ANSI 53 for activated carbon systems and NSF/ANSI 58 for reverse osmosis, both of which now include PFOA and PFOS reduction requirements. Look for those contaminants named on the performance data sheet.
What is the difference between NSF/ANSI 42 and 53?
Standard 42 covers aesthetic effects — chlorine taste and odor, particulates. Standard 53 covers health effects such as lead, cysts and VOCs. Almost every filter holds 42; 53 is the one that matters for a contaminant with a health consequence.
Sources
- NSF — Forever Chemicals and the Advancement of Filtration Standards — Why NSF P473 was retired into NSF/ANSI 53 and 58 in June 2021
- Brita — lead reduction and NSF/ANSI 53 certification for the Elite filter
- Clearly Filtered (manufacturer)
- US EPA — Our Current Understanding of the Human Health and Environmental Risks of PFAS — Regulator overview of PFAS persistence and health endpoints
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Written by Selena H., owner of Glass & Cotton.