SUMMARY OF DR. MARC EDWARDS’ LATEST RESEARCH

• Dr. Edwards continued his prior work examining the roles of aluminum and chlorine as potential promoters of copper pitting.
• His recent tests also looked at how flow (versus stagnant water) and different pH levels would impact copper pitting tendencies.
• He used off-the-shelf copper pipe (soft copper, hard copper and copper couplings) and "synthetic" water. His man-made water contained approximately the same dissolved salts (hardness, alkalinity, sulfate, etc.) as does water at WSSC. The water meets all federal EPA regulations and was actually "cleaner" than federal standards as it did not contain any natural organic matter (NOM). Some NOM are natural corrosion inhibitors.
• The combination of high pH, aluminum and chlorine levels, and no NOM gave every indication of initiating pitting of copper in the lab for the first time. (Note: this does not mean a pinhole leak formed in the pipe, although the extent of corrosion observed in just 20-28 days testing was impressive by any measure.)
• The impact of higher pH contradicts the conventional scientific wisdom that higher pH is generally less corrosive to copper. For example, higher pHs are used to reduce copper leaching to water in order to meet federal lead/copper rule regulations. This is an industry standard practice reinforced by the EPA lead/copper rule recommendations. The observation that higher pH may also increase the likelihood of pitting when aluminum and chlorine are present is especially troubling, given that so many utilities around the country have recently increased pH to control lead and copper leaching to water. It is important to note that previous research indicates that higher pH by itself (without the presence of aluminum and chlorine) does not cause pitting of copper tube.
• The adverse impacts of aluminum on copper pitting corrosion were also unexpected. Earlier published work actually supported the idea that such films would be beneficial in preventing aspects of pipe corrosion. In some instances, in fact, utilities were considering purposefully forming such aluminum films on pipes to aid in corrosion control. This work shows that these films, at least at higher pHs and in the presence of free chlorine, can actually increase the likelihood of pitting corrosion. Given this circumstance, utilities should carefully monitor aluminum residuals in treated drinking water as well as possible aluminum leaching from cement lined pipes (factory or lined as part of maintenance practices), since it appears that even trace levels of aluminum can help initiate pitting problems under some circumstances.
• His work indicates that EPA requirements coupled with best industry practices including: NOM removal, possibly cleaning/lining and installing new cement-lined pipes, traces of aluminum in water, and improved general corrosion control by raising pH, may promote copper pipe pinhole leaks.
• Of specific interest to WSSC is his work that raises questions of the effectiveness of orthophosphate to slow or stop copper pitting corrosion at higher pH levels.
• Dr. Edwards has no basis to offer utilities specific recommendations at this point (treatment/maintenance practices). However, it can be generally observed that enhanced NOM removal, higher aluminum in water supplied to consumers’ homes, and higher levels of free chlorine must now be considered as likely contributing causes to increased pitting frequency. It appears that the obvious public health benefits of free chlorine, the likely public health benefits of NOM removal, and the reduction in copper and lead leaching to drinking water at higher pH need to be weighed against the possible likelihood of higher pinhole leaks. These apparent conflicts must be resolved with considerable urgency given the extremely high costs of pinhole leaks to consumers. It would be highly desirable to determine approaches that could allow achievement of known and suspected public health goals without also causing increased pinhole leaks (if future research verifies his recent results).
• Dr. Edwards is receiving calls every day from utilities and consumers across the country. He estimates he has heard of a different impacted system every three days for the last few weeks. This is in addition to the 10-20 outbreaks he has been aware of the last few years. It is not possible to discern whether the problem is getting worse nationally, or whether a greater percentage of those impacted are calling him for help, although he strongly suspects the problem is getting worse.

HIGHLIGHTS

• It’s very clear that we are in completely uncharted waters. These are new, unanticipated findings. A very poor current state of knowledge still exists on this subject.
• The impacts of high chlorine, aluminum and pH, and removal of NOM suggest that standard industry best practices and EPA regulations (NOM removal, lead/copper rule, etc.) may be combining to cause a major problem for homeowners across the country with copper pipes.
• Recent results about the effect of pH are in direct conflict with the longstanding scientific observation that higher pH leads to fewer copper corrosion problems.
• Additional research needs to be done to understand this problem before it can be solved with confidence. There are still other unknown factors thought to be involved in causing this problem nationally.
• No one -- not the copper industry, water utilities or EPA -- could have anticipated this reaction. The adverse impacts of NOM removal on copper pitting were predicted in a peer reviewed journal article in 1994. The apparent impact of Cl2 and Al was discovered only during this project in work directly funded by WSSC and the Copper Development Association (CDA). WSSC funded the first phase of this research and CDA funded the current phase.
• WSSC, CDA and local plumbers have been working together for more than two years to solve this problem for homeowners impacted by pinhole leaks in the WSSC service area.
• In light of Dr. Edwards’ latest research indicating federal water chemistry regulations may play a role in this problem, EPA needs to get involved in this national issue.
• There is a commitment from all parties to continue working together to hopefully find a solution to this costly problem. A commitment from EPA to get involved with funding would be helpful.

NEXT STEPS

• In the short term, while Dr. Edwards’ findings did not lead to concrete recommendations that could immediately stop this problem, they do point to promising research ideas that may do so in the near future.
• Dr. Edwards requested that CDA fund a replication of the study and a peer review. This is necessary to assure that the highest scientific standards are upheld in this investigation, as the results potentially impact millions of homeowners nationally and may impact EPA regulations.
• Because his work raises a question of effectiveness of orthophosphate at higher pH levels, WSSC is working with AWWARF to secure additional funds to test the use of orthophosphate and water at different pH levels. WSSC has committed approximately $23,000 to this effort and is hopeful AWWARF can fund the remaining $25,000. The tests should last approximately 3 to 4 months.
• Update Montgomery and Prince George’s County officials of latest findings after orthophosphate / pH tests are complete.
• Continue communication efforts to WSSC customers.
• Continue work with task force.
• Since this work raises questions about the potential roles of federal water chemistry regulations in copper pipe pitting, EPA needs to get involved in this national issue.