Certification · 7 min
NSF/ANSI water-filter certification reference
A practical guide to Standards 42, 53, 55 and 58—and why a standard number is not the same as a claim for every contaminant.
- Author
- WaterFilterHelp Editorial Team
- Canadian home-water research and consumer education
- Reviewed by
- WaterFilterHelp Standards Review
- Fact-checked against official Canadian guidance and certification sources
- Last reviewed
- 2026-08-23
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Read the claim, not only the number
Certification means an independent body evaluated specified safety and performance requirements. It does not mean a product removes every contaminant covered somewhere in that standard. Verify the exact model and reduction claim in the certifier’s listing.
NSF/ANSI 42
Standard 42 covers aesthetic effects such as chlorine taste and odour. A 42-certified carbon filter is not automatically certified for lead, PFAS or microorganisms.
NSF/ANSI 53
Standard 53 covers health-effect reduction claims for filtration products. Claims can include lead and certain PFAS, but only when the exact product listing says so.
NSF/ANSI 58
Standard 58 applies to reverse-osmosis systems. Check the model’s claims for the contaminant in your lab report; RO certification alone is not a blanket removal promise.
NSF/ANSI 55 Class A and Class B
Class A UV systems are intended to disinfect contaminated water that is otherwise visually clear. Class B systems provide supplemental treatment only for water already considered safe. UV does not remove dissolved metals, nitrate, PFAS or hardness.
NSF/ANSI 62
Standard 62 applies to residential distillation systems. As with every standard, confirm the exact reduction claims, capacity and maintenance requirements.