NSF 42 vs 53 vs 401 for fridge filters
Last checked October 28, 2026
NSF/ANSI 42 is for aesthetic claims such as chlorine, taste and odor. NSF/ANSI 53 is for health effect claims such as lead and cysts. NSF/ANSI 401 is for emerging compounds such as some medicines, pesticides and BPA. A filter is listed only for the specific claims named in its listing.
| Standard | NSF's title | Example claims in fridge filter listings |
|---|---|---|
| NSF/ANSI 42 | Drinking Water Treatment Units, Aesthetic Effects | Chlorine, taste and odor, particulates |
| NSF/ANSI 53 | Drinking Water Treatment Units, Health Effects | 2,4-D, Asbestos, Atrazine, Benzene, Carbofuran, Chlorobenzene |
| NSF/ANSI 401 | Emerging Compounds/Incidental Contaminants | Atenolol, Bisphenol A, Carbamazepine, DEET, Estrone, Ibuprofen |
Example claims are from the NSF listing for everydrop Filter 4 (EDR4RXD1), read October 28, 2026. Each filter's own listing names its own claims.
What this means when you shop
- If you care about lead, look for NSF/ANSI 53 with lead reduction named in the listing for your exact model.
- Many replacement brands sell a basic version listed to 42 only. In our data that is 40% of 67 replacement models.
- 401 is an extra; check whether the genuine filter you are replacing has it.
Sources
- NSF standard names: info.nsf.org/certified/dwtu (read October 28, 2026)
- Example listing: https://info.nsf.org/Certified/DWTU/Listings.asp?TradeName=EDR4RXD1&submit3=Search