| Feature | NSF/ANSI 61 | NSFS 347 2021 | |--------|--------------|----------------| | | All materials contacting drinking water (pipes, valves, cements, coatings) | Only nonmetallic gaskets in water/wastewater systems | | Testing focus | Chemical leaching only | Chemical + mechanical + aging | | Wastewater included? | No | Yes (NSF/ANSI 600 for wastewater) | | Mechanical tests | None | Compression set, creep, tensile strength | | Certification validity | 5 years | 3 years (shorter due to aging risks) |