NSF P473 Certification Explained: The Only Standard That Tests for PFAS

What NSF P473 Actually Tests For

NSF/ANSI P473 was created in 2016 specifically to address PFAS in drinking water. It tests for the reduction of two compounds:

• PFOA (perfluorooctanoic acid) — used in non-stick coatings, food packaging, and stain repellents
• PFOS (perfluorooctane sulfonate) — found in firefighting foam, water-resistant fabrics, and industrial applications

To pass, a filter must reduce both PFOA and PFOS to below 70 parts per trillion (the original EPA health advisory level). Many certified filters go far beyond this. The Clearly Filtered pitcher, for example, removes 99.7% of PFOA and 99.9% of PFOS.

One thing to know: NSF P473 only covers PFOA and PFOS. There are over 14,000 PFAS compounds. The standard does not test for all of them. But PFOA and PFOS are the two most studied, most common, and most regulated. If a filter removes those two, it likely reduces other PFAS as well, though that is not guaranteed without testing.

Why NSF 42 and NSF 53 Are NOT Enough

Most people see "NSF certified" on a box and think their filter handles everything. It does not. Each NSF standard covers different contaminants. Here is what each one does:

Here is the bottom line: a filter can hold NSF 42, NSF 53, and NSF 401 all at the same time and still fail to remove a single PFAS molecule. The only way to know if a filter handles PFAS is the P473 stamp — or independent lab testing showing PFAS reduction.

"Tested to NSF Standards" vs "NSF Certified" — The Marketing Trick

This is where most brands mislead buyers. There is a big difference between these two phrases:

How to tell which one a brand has: go to the NSF certification database and search for the brand name. If the product shows up under Standard P473, it is certified. If it does not show up, the brand is using the weaker "tested to" claim.

This matters because without independent verification, you are trusting the company to honestly report its own results. Some do. Some do not.

Filters That Actually Hold NSF P473 Certification

As of early 2026, the list of NSF P473 certified consumer products is short. That is because certification is expensive and time-consuming. Here are the verified ones:

Popular Filters That Do NOT Have NSF P473

Why Brita, PUR, and ZeroWater Cannot Remove PFAS

It comes down to carbon type and pore size. All three brands use granular activated carbon (GAC). GAC works by trapping contaminants in tiny pores as water flows through. It is great for chlorine, bad taste, and some organic compounds.

But PFAS molecules are small and they resist bonding to standard carbon surfaces. GAC pores are too large to catch them. The water flows through, and the PFAS go right along with it.

To trap PFAS, you need one of these technologies:

• Catalytic carbon — specialized carbon with surface chemistry that binds PFAS molecules
• Carbon block with tight pore structure — compressed carbon with pores small enough to physically block PFAS
• Reverse osmosis membrane — pores measured in angstroms that block nearly everything, including PFAS
• Ion exchange resin — targets charged PFAS molecules specifically (used in some industrial systems)

Brita, PUR, and ZeroWater use none of these. That is not a knock on them — they were designed before PFAS was a household concern. But if PFAS is your reason for buying a filter, these three will not solve the problem. Read our full breakdown of whether Brita removes PFAS.

How to Verify a Filter's Certification Yourself

1. Go to the NSF Drinking Water Treatment Units page.
2. Search by brand name or product name.
3. Look for "Standard P473" in the certifications column.
4. If it is not listed under P473, the product is NOT certified for PFAS removal — no matter what the box says.

This takes about 30 seconds and will save you from buying the wrong filter.

Frequently Asked Questions