Critical evaluation of the NSF 61 Section 9 test water for Lead

The authors evaluated the NSF 61 Section 9 protocol from the perspective of test water chemistry and lead‐leaching propensity. Overall, the test water proved representative of a typical water supply. However, some chloraminated waters with lower pH and lower alkalinity can be more aggressive than the Section 9 water, especially after months of exposure. As a result, products that are certified under NSF Section 9 might still cause compliance problems with US Environmental Protection Agency regulations for lead. Moreover, similar problems may be expected to affect approximately 16% of the US population served by private water supplies and cistern‐type systems, which also are considered aggressive to lead leaching. To account for these concerns, the authors recommend that the Section 9 pass/fail criterion be tightened and that product information be made available that details possible limitations of the products relative to lead leaching in certain corrosive water supplies.