Dear Water Conditioning & Purification:

We would like to respond to issues raised in Mr. Purkiss’ letter of October 2005. Specifically, he states that we omitted certain requirements in NSF 61 in our testing of lead leaching from brass and that this led to a whole host of conclusions in our August Journal American Water Works Association paper with which NSF International disagrees and that he felt may be misleading to the general public.

The only omitted NSF requirement that Mr. Purkiss cites is that arising from revisions to the NSF standard made in March 2005. This revision requires that all exposure water must now be made fresh daily and stored in closed containers. Mr. Purkiss acknowledges that this revision was made based on results of our own experiments, which were completed in 2003 and that were finally published after peer review in August 2005. The fact remains that the testing we conducted in 2003 fairly represent requirements of NSF 61 Section 8 before March 2005.

Mr. Purkiss further asserts that if the waters had been made up according to the revised NSF standard, that the solid lead device would not have passed the standard. Additional research, not yet conducted, would be necessary to verify his statement. In any case, the newly revised NSF standard cannot retroactively decrease the likelihood of lead leaching from installed products achieving NSF certification as it existed before March 2005.

Mr. Purkiss also takes issue with our suggestion that the NSF standards development process is not open to public scrutiny. In response, we think it is necessary to point out that the high level of cooperation between NSF and the authors did not always exist. One of the authors (Edwards) first became aware of potential deficiencies with the NSF 61 Section 8 standard while serving as an expert witness in a California Proposition 65 lawsuit related to leaded brass. At the time, experts paid by the other side in the lawsuit had conducted tests and completed modeling that asserted how extraordinarily aggressive the NSF Section 8 pH 5 water would be relative to lead leaching from brass. In response to a direct question regarding whether or not the pH 5 water contained orthophosphate, one of the experts responded “I don’t believe so.” Following that testimony, three direct inquiries were made by one of us (Edwards) to NSF to determine whether the NSF 61 Section 8 pH 5.0 water really did contain 75 mg/L orthophosphate. This is important because orthophosphate is added to many potable waters specifically to inhibit lead leaching. NSF never responded to these repeated inquiries. We later determined that the pH 5 water did contain this high level of phosphate and that it was inhibiting lead leaching to the test water.

This experience, coupled with the fact that an electronic copy of the NSF 61 Standard costs $600 to obtain and review (nor is information readily available on their website), provides a valid basis for our criticism regarding difficulty of public scrutiny in the recent past.

We do acknowledge that NSF has been commendably responsive and cooperative since we first revealed results of our study to them and indicated our intent to publish a peer reviewed journal article. We look forward to future cooperation with NSF in developing improved standards upon which the water industry, regulators and manufacturers can rely.

Sincerely,
Dr. Marc Edwards
Michael R. Schock

Share.

Comments are closed.