IAPMO vs NSF vs WQA

IAPMO R&T, NSF and WQA are three of the five ANSI-accredited bodies that EPA lists as certifying home filters for PFAS reduction, and all three certify against the same NSF/ANSI standards. A filter needs only one of them to list a claim, which is why a model can appear in one directory and not in another.

What they share

• Accreditation. EPA's home filter fact sheet names five ANSI-accredited third-party certification bodies: CSA Group, IAPMO R&T, NSF, UL and WQA, each with its own registered mark.
• The same standards. "NSF/ANSI 53" names a standard, not the certifier. Brita's data sheet for its Elite filter shows IAPMO R&T, NSF and WQA each certifying the same cartridge against NSF/ANSI standards.
• Ongoing checks. IAPMO R&T's certificates describe testing of samples and periodic surveillance of the supplier's factory. Michigan's PFAS Action Response Team says certified filters must be retested periodically, with factories inspected every year.

One filter, three certifiers

Brita's Elite cartridge (OB06) shows how listings split. Its data sheet says:

• IAPMO R&T certified it under NSF/ANSI 53 for lead in nine named Brita pitcher models.
• NSF certified two pitchers with it, the Pacifica (OB41) and the Tidal (OB63), under NSF/ANSI 53 for lead.
• WQA certified it under NSF/ANSI 42, 53 and 401 for the claims the data sheet specifies.

IAPMO's own listing shows "Lead" for the Elite cartridge in pitchers such as the Everyday, Huron and Tahoe. By the data sheet's account, NSF's lead certification covers two pitchers and IAPMO's covers nine. EPA notes that some filters carry more than one certification mark.

How each publishes listings

• IAPMO R&T posts each certification as a certificate in its Product Listing Directory: file number, standard and edition, listed models and replacement cartridges, rated capacity where the standard sets one, and the reduction claims. Each page gives the date it is current as of. PUR's NSF/ANSI 53 certificate is a typical example.
• NSF and WQA run their own searchable directories, which EPA links from its PFAS filter page: NSF's listings and WQA's directory.

Whichever body certified a filter, EPA's advice is to check its directory for testing information or to see if the product has been certified to treat PFAS. Claims missing from the box may be on the performance data sheet, the certifier's directory or the maker's website.

Why a filter can be listed by one and not another

1. The maker picks the certifier. IAPMO R&T's program page is written to manufacturers deciding which body to use: "Before you choose a third-party certification body, contact us". A brand can also split claims across bodies, as Brita does.
2. Listings are per model and per cartridge. PUR's NSF/ANSI 53 certificate lists the same pitcher twice: with the PPF900Z filter it shows no lead or PFAS claim, and with the PPF951K filter it shows "Lead" and "Total PFAS".
3. The listed name may not match the box. Waterdrop's G3 PFAS listing is issued to Qingdao Ecopure Filter Co. Ltd, with Waterdrop as the brand in the model rows. Search by model and cartridge number as well as by brand.
4. A listing is a snapshot. Each IAPMO certificate states the date it is current as of, so check again before you buy.

What this means on our site

We check IAPMO R&T's directory automatically. NSF and WQA listings are checked by hand, product by product, and those checks are still in progress. We do not check UL or CSA yet. If a brand cites NSF or WQA and IAPMO has no matching listing, the claim shows as Brand says certified, not found in IAPMO's listing; check NSF until someone checks those directories. That label means the claim is not yet confirmed by a listing we checked. It does not mean the claim is unsupported.

The full method is in How we decide "certified" and on the methodology page. What each standard covers is in NSF/ANSI 42 vs 53 vs 58 vs 401 vs P473 explained.