How we decide "certified"

We call a filter claim certified only when a certification body's public listing shows that claim for that exact model or its replacement cartridge. We read listings; we do not test, use or lab-test any product, and a brand's own wording, logos or lab reports are not enough on their own.

The rule, step by step

1. Record the claim. We copy each lead, PFAS or other reduction claim from the brand's product page and performance data sheet word for word, with the page address and the date.
2. Search the listings. We search IAPMO R&T's Product Listing Directory by model number, brand name and listed company, then open every matching certificate.
3. Match the model. A certificate counts only if it is active, its model number or replacement cartridge number matches the product, and its listed company or brand matches the maker.
4. Match the contaminant. The claim must appear in that model's row. A PFOA/PFOS or Total PFAS listing backs a PFOA or PFOS claim. A brand claim for "PFAS" in general is matched to a Total PFAS listing, or to a PFOA/PFOS listing with a note that it covers those two.
5. Keep the evidence. Each match keeps the certificate link and the date we checked it.

The cartridge matters. PUR's NSF/ANSI 53 certificate lists the same pitcher twice: with one filter it shows no lead or PFAS claim, and with another it shows "Lead" and "Total PFAS". The claim belongs to the listed cartridge, not to the pitcher.

What does not count

• Materials-only standards. NSF/ANSI 61 and 372 cover what a product's parts put into water and how much lead they contain. A 372 certificate says its products were verified with weighted average lead content of 0.25% or less, and it lists no reduction claims.
• "Tested to" or "meets" wording without a listing.
• A brand's own lab reports, however detailed.
• Another model's listing, unless it names this product's cartridge.

Which certifiers we check

• IAPMO R&T: checked automatically for every product, one search at a time.
• NSF and WQA: checked by hand, one product at a time. As of 16 Oct 2026 no hand checks are recorded, so no NSF or WQA listing counts yet. You can search NSF's listings and WQA's directory yourself.
• UL Solutions and CSA Group: EPA counts both among the ANSI-accredited bodies that certify home filters. We do not check them yet.

A missing IAPMO listing is therefore not proof that no certificate exists.

The labels you will see

• Certified (IAPMO listing, checked 16 Oct 2026): an active IAPMO R&T listing for that model or its cartridge shows the claim. If an NSF or WQA listing is checked by hand and shows the claim, the label names that certifier and the check date instead.
• Brand says certified, not found in IAPMO's listing; check NSF: the brand says the claim is certified, and IAPMO's directory shows no listing for it on that model. When the brand names NSF or WQA, a hand check of those listings settles it.
• Brand claim, no certification cited: the brand states the reduction ("removes", "tested", "meets") without saying it is certified, and IAPMO lists nothing for it.

In comparison tables, No claim means the brand does not claim to reduce that contaminant. When a listing shows a reduction the brand does not mention, we show the listing too.

What "certified" tells you, and what it does not

Certification means a certifier tested the model against the standard and keeps checking it. IAPMO R&T describes its program as testing of samples plus periodic surveillance of the supplier's factory. It is not a promise about your tap. EPA says certification standards as of April 2024 do not yet indicate that a filter will remove PFAS down to the levels EPA has now set, and that filters work only if maintained according to the manufacturer's instructions.

Check a claim yourself

1. Find the model and replacement cartridge numbers on the box or the performance data sheet.
2. Search for them in IAPMO R&T's directory, NSF's listings and WQA's directory. EPA suggests checking the certifier's directory whenever you are in doubt.
3. Open the listing and find your contaminant on your model's row.

More detail: the methodology page, IAPMO vs NSF vs WQA and NSF/ANSI 42 vs 53 vs 58 vs 401 vs P473 explained.