United States
Environmental Protection
Agency
RESEARCH PROJECT
National Risk Management Research Laboratory
Water Supply and Water Resources Division
Treatment Technology Evaluation Branch
IMPACT OF WATER CHEMISTRY ON LOCALIZED CORROSION OF COPPER PITTING
IMPACT STATEMENT
This project will help identify what waters are problematic in
causing the corrosion of copper pipes and improve
understanding of how water distribution leads to corrosion.
This project will also focus on the prevention of pinhole leaks
and how to reverse them once they occur. The U.S.
Environmental Protection Agency (EPA) plans to utilize the
results derived from this project to help save infrastructure
for homeowners and create a better relationship between
water chemistry and, plumbing life expectancy and
conditions.
BACKGROUND:
Historically, prior to the attention drawn to localized pitting, EPA focused lead and copper corrosion research on metal
levels in consumer's tap water. Localized pitting corrosion has been recognized as a source of copper pipe failure in
household plumbing systems. Many communities experience pinhole leaks in household plumbing that eventually lead
to pipe failure and the need for costly plumbing replacement. Over time, pitting corrosion research has led to a variety
of theories regarding the initiation and broadcast of pitting corrosion, and descriptions of the physical and mineralogical
properties of the areas of attack. EPA has been collaborating with communities, Pegasus, and student services
contractors on this particular project. Observations of neighboring water systems have proven to be a little more
informative than experimentations. Despite having the same water source, treatment approach and finished water
quality, the neighboring water systems have not reported copper pitting problems. The sole difference in neighboring
water systems is that they add some form of phosphate to their waters. Conclusively, the observations suggest that
phosphate compounds prevent pitting corrosion of copper in some way.
Localized copper corrosion in water has been categorized into three different types based on chemistry and physical
features. The types include cold-water, hot-water, and soft-water. Out of the three different types, there has been more
emphasis placed on soft-water pitting. Soft-water copper pits have been described as fairly wide and shallow with an
exterior layer of bronchanite and/or malachite covering a layer of crystalline red-brown cuprite over the corroded
copper surface. The corrosion deposits that result from this are released into the water and can lead to water blockage.
Waters typically associated with soft-water pitting have low conductivity, low alkalinity, and relatively high pH.
DESCRIPTION:
The Office of Research and Development's National Risk Management Research Laboratory has funded this research
project in support of its Aging Water Infrastructure Research Program. This project will improve EPA's understanding of
localized corrosion of copper in water. The project will document full-scale case studies and conduct bench- and pilot-
National Risk Management Research Laboratory
Water Supply and Water Resources Division
-------
scale laboratory tests, and extensive analysis of pipes removed from community distribution systems that have failed
copper plumbing due to localized corrosion. Project results will improve our understanding of localized corrosion and be
the basis for proposed strategies in how the problem can be resolved.
This project will help identify what waters are problematic in causing the corrosion of copper pipes and improve
understanding of how drinking water quality is related to localized corrosion. This project will also focus on the
prevention of pinhole leaks and how to reverse them once they occur. EPA plans to utilize the results derived from this
project to help save infrastructure in households and create a better understanding of the relationship between water
chemistry and, plumbing life expectancy and conditions.
EPA GOAL: Goal #2 - Clean & Safe Water, Objective 2.1.1- Water Safe to Drink
ORD MULTI YEAR PLAN: Drinking Water (DW), Long Term Goal - DW-2 Control, Manage, and Mitigate Health Risks
RESEARCH PARTNERS: Pegasus and student services contractors
EXPECTED OUTCOMES AND IMPACTS:
The expected outcomes and impacts of this project increased acceptance of new and innovative technologies by
decision makers who adopt, regulate, and design infrastructure technologies; extended service life and functionality of
existing conveyance systems; reduced life cycle cost; improved prioritization of critical infrastructure to inspect, monitor,
and assess the performance of rehabilitation; reduced localized corrosion of copper in water; and reduced infrastructure
failures. This project is expected to provide assistance and guidance in what water chemistries are problematic and to
apply the most appropriate treatment to extend life of pipes.
OUTPUTS:
Current and future outputs of the project will consist of a technology forum; white paper; peer-reviewed journal articles;
and conference proceedings.
RESOURCES:
Aging Water Infrastructure Research Program: http://www.epa.gov/awi/
Corrosion, Scaling, and Metal Mobility Research: http://www.epa.gov/nrmrl/wswrd/cr/index.html
Pitting Corrosion of Copper in High-pH and Low-Alkalinity Waters:
http://www.epa.gov/nrmrl/wswrd/cr/corr res copper ai2.html
Lytle, D. A. and Schock, M. R. Pitting of Copper in High pH and Low Alkalinity Waters, Journal of the AWWA 100 (3),
2008:115-128. http://www.awwa.org/
CONTACTS:
Darren Lytle, Principal Investigator - (513) 569-7432 orlytle.darren@epa.gov
Steven Doub, Media Relations - (513) 569-7503 or doub.steven@epa.gov
Michelle Latham, Communications - (513) 569-7601 or latham.michelle@epa.gov
National Risk Management Research Laboratory www.epa.gov/nrmrl EPA/600/F-09/013
Water Supply and Water Resources Division ' October 2009
------- |