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NSF/ANSI 42: Taste, odor and appearance

Official title: Drinking Water Treatment Units - Aesthetic Effects

A product certified to NSF/ANSI 42 was tested to reduce things that affect taste, smell or look, not health. It is certified only for the specific claims on its listing.

What it can cover

  • Chlorine, for taste and odor (listing claim: "Chlorine Reduction")
  • Chloramine (listing claim: "Chloramine Reduction")
  • General taste and odor (listing claim: "Taste and Odor Reduction")
  • Particles, graded by size class (listing claim: "Nominal Particulate Reduction")
  • Zinc (listing claim: "Zinc Reduction")
  • Iron, manganese and total dissolved solids (TDS), which NSF lists as possible 42 claims

What it does not

  • Lead. Lead reduction is a health claim made under NSF/ANSI 53 or 58.
  • PFAS, including PFOA and PFOS
  • Cysts, bacteria or viruses
  • Nitrate, arsenic or fluoride
  • VOCs and trihalomethanes (TTHM)

The usual mistake

Many sites say a filter certified to NSF/ANSI 42 removes lead. It does not. Every 42 claim is aesthetic, and lead reduction is a separate health claim under NSF/ANSI 53 or 58.

The fine print

  • Testing also covers material safety, including lead content under NSF/ANSI/CAN 372, and structural strength.
  • EPA suggests pairing a 53 lead claim with a 42 Class I particulate claim, because some particles can carry lead.
  • WQA listings word the chlorine claims as "Aesthetic Chlorine" and "Aesthetic Chloramine." NSF lists iron and manganese as 42 claims, but its listing search showed no products with them on Oct. 4, 2026.
  • EPA names five ANSI-accredited certifiers that test filters to these standards: CSA Group, IAPMO R&T, NSF, UL Solutions and WQA.
  • A listing from any of them is a real certification.
  • WQA says its own accreditation comes from ANAB and SCC.

Claims to look for

ContaminantClaim on the listing
Manganese
  • Manganese
  • NSF lists manganese as a possible NSF/ANSI 42 claim, but neither NSF nor WQA listings showed a product with it on Oct. 4, 2026. WQA has no manganese claim.
Chlorine
  • Chlorine Reduction
  • Aesthetic claim for taste and odor. WQA wording: "Aesthetic Chlorine."
Chloramine
  • Chloramine Reduction
  • Aesthetic claim. Chloramine is a separate claim from chlorine. WQA wording: "Aesthetic Chloramine."
Iron
  • Iron
  • WQA listing wording, under NSF/ANSI 42. On Oct. 4, 2026, WQA showed it only on whole-house systems from one maker. NSF lists iron as a possible 42 claim, but its listing search showed no products with it.
Hydrogen sulfide
  • Hydrogen Sulfide
  • WQA listing wording, under NSF/ANSI 42. On Oct. 4, 2026, WQA showed it only on whole-house systems from one maker. NSF's 42 page does not name hydrogen sulfide, and NSF's listing search offers no such claim.

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 42.

TapBuff earns a commission if you buy through some links on this page. It does not change which standard or filter we name. As an Amazon Associate, TapBuff earns from qualifying purchases. How TapBuff makes money

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. Find WQA Certified Products (Gold Seal listings by standard and claim), Water Quality Association. Checked Oct. 4, 2026.
  5. Product Certification, Water Quality Association. Checked Oct. 4, 2026.
  6. Consumer Tool for Identifying Point-of-Use and Pitcher Filters Certified to Reduce Lead in Drinking Water (EPA/600/F-24/143, June 2024), U.S. EPA. Checked Oct. 4, 2026.
  7. A Consumer Tool for Identifying Point of Use (POU) Drinking Water Filters Certified to Reduce Lead (EPA/600/F-18/335, December 2018), U.S. EPA. Checked Oct. 4, 2026.