NSF/ANSI 58: Reverse Osmosis Drinking Water Treatment Systems
December 18, 2025
Reverse osmosis systems and components fall within the scope of NSF/ANSI 58. To learn about the requirements and certification process for this standard, check out this informational piece.
This standard includes requirements addressing various aspects of point-of-use (POU) reverse osmosis (RO) systems, including:
- Safety of materials in contact with drinking water (including content in accordance with NSF/ANSI/CAN 372)
- Structural integrity
- TDS (total dissolved solids) reduction performance
- Efficiency rating
- Recovery rating
- Contaminant reduction performance
- Information for the end user.
Claims available under NSF/ANSI 58
Standard NSF/ANSI 58 includes test procedures to verify various claims that can be made for your RO system, including:
Required
- TDS (total dissolved solids) reduction.
Optional
- Cyst reduction
- Hexavalent and trivalent chromium reduction
- Arsenic reduction
- Nitrate/nitrite reduction
- Cadmium reduction
- Lead reduction
- Barium reduction
- Turbidity reduction
- Fluoride reduction
- Copper reduction
- VOC reduction
- Asbestos reduction
- Perchlorate reduction
- Radium 226/228 reduction
- Selenium reduction
- Pentavalent arsenic reduction.
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