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NSF/ANSI 401: Emerging contaminants

Official title: Drinking Water Treatment Units - Emerging Compounds/Incidental Contaminants

Covers filters tested to reduce trace contaminants that EPA does not regulate, such as some drugs, pesticides, BPA and microplastics. Each compound is its own claim.

What it can cover

  • Atenolol
  • Bisphenol A (BPA)
  • Carbamazepine
  • DEET
  • Estrone
  • Ibuprofen
  • Linuron
  • Meprobamate
  • Metolachlor
  • Microplastics
  • Naproxen
  • Nonylphenol
  • Phenytoin
  • TCEP
  • TCPP
  • Trimethoprim

What it does not

  • PFAS, including PFOA and PFOS. PFAS claims are under NSF/ANSI 53 or 58.
  • Lead and other EPA-regulated contaminants
  • Drugs and chemicals not on the list above

The usual mistake

Saying a 401 filter "removes pharmaceuticals" in general. Each claim covers one named compound, and a product may hold only some of them.

The fine print

  • NSF listings word each claim as the compound name plus "Reduction," such as "Bisphenol A Reduction" and "Microplastics Reduction." NSF describes 401 as covering up to 15 individual contaminants.
  • Its listing search shows 16 claims: 15 chemicals plus microplastics.
  • NSF says these compounds turn up at trace levels and are not yet regulated by EPA or Health Canada.
  • NSF posted a 2026 edition of this standard.

Filters TapBuff has checked against a listing

Every certification below links to the certifier’s own listing. A filter appears here only if its listing shows NSF/ANSI 401.

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Sources

  1. NSF Standards for Water Treatment Systems, NSF. Checked Oct. 4, 2026.
  2. NSF/ANSI 42, 53 and 401: Filtration Systems Standards, NSF. Checked Oct. 4, 2026.
  3. Search for NSF Certified Drinking Water Treatment Units (standards and reduction claims lists), NSF. Checked Oct. 4, 2026.
  4. Water Filters FAQs, NSF. Checked Oct. 4, 2026.
  5. Joint Committee on Drinking Water Treatment Units: recent documents (2026 editions of 44, 55, 62, 244, 401), NSF. Checked Oct. 4, 2026.
  6. Find WQA Certified Products (Gold Seal listings by standard and claim), Water Quality Association. Checked Oct. 4, 2026.