Examining the Efficacy of Copper-Silver Ionization for Management of Legionella
MARK LECHEVALLIERAMERICAN WATER WORKS ASSOCIATION (AWWA), WATER SCIENCE, MARCH 2023 IntroductionThis review article examined more than 80 sources of literature and studies related to copper-silver ionization system efficacy, design, maintenance, and operations, and the impact water chemistry has on its performance. ResultsPrevious research indicates that copper-silver ionization is effective for Legionella control. Other key findings of this study include: ConclusionThe report concludes that using copper-silver ionization to control Legionella and other opportunistic pathogens is highly effective when the units are properly designed, maintained, and operated. Full study
Controlling Legionella in Hospital Drinking Water: An Evidence-Based Review of Disinfection Methods
YUSEN LIN, JANET E. STOUT, VICTOR YUCAMBRIDGE UNIVERSITY PRESS, INFECTION CONTROL AND HOSPITAL EPIDEMIOLOGY, FEBRUARY 2011 IntroductionThis study reviewed the efficacy of different disinfection methods for controlling Legionella in hospitals, including copper-silver ionization, chlorine dioxide, hyperchlorination, monochloramine, UV, point-of-use filtration, and superheat-and-flush. The four criteria each disinfection method must meet to validate efficacy include: ResultsA summary of findings for each disinfection method is included below. Copper-silver ionization– Only method validated by the four criteria– Easy installation and maintenance– Not impacted by higher temperatures– Residual levels are maintained for a prolonged period– Efficacy declines in pH greater than 8.5 Chlorine dioxide– Penetrates biofilm– Effective over a wide range of pH levels– Creates harmful byproducts– Difficult to maintain residual levels Monochloramine– Penetrates biofilm– Effective over a wide range of pH levels– Can cause anemia in dialysis patients– On-site generation can be complicated Hyperchlorination– Most expensive and unreliable of all methods– Causes corrosion– Does not penetrate biofilm– Introduces carcinogens into the water Point-of-use filtration– Effective against Legionella and Mycobacterium– Provides immediate protection making them a good option for outbreaks– Not cost-effective for long-term use UV– Non-chemical– Works best when installed on the incoming water supply– Does not provide systemic disinfection Superheat-and-flush– Effective in emergencies– Not effective for prolonged use– Limited to hot water lines ConclusionThere are several viable methods for controlling Legionella, but copper-silver ionization was the only method validated by the four criteria at the time of this study. The researchers concluded that “copper-silver ionization appears to be the best available technology today for controlling Legionella colonization in hospital water systems.” They suggested that rigorous maintenance plans, regular monitoring of ion concentrations, and frequent Legionella testing are necessary to ensure long-term success. Full report
Use of Copper-Silver Ionization for the Control of Legionella in Alkaline Environments at Healthcare Facilities
DAVID M. DZIEWULSKI, ERIN INGLES, NECULAI CODRU, JOHN STREPELIS, DIANNA SCHOONMAKER-BOPPELSEVIER, AMERICAN JOURNAL OF INFECTION CONTROL, JULY 2015 IntroductionThis study examined two healthcare facilities using copper-silver ionization to control Legionella in alkaline water conditions. One facility was an acute care facility with a pH range of 8.7-9.9. The other was a long-term care facility with a pH range of 8.9-9.7. Both had previously used disinfection methods without success, including superheat-and-flush, hyperchlorination, and chlorine dioxide. ResultsAcute care facilityThe acute care facility reported six cases of Legionnaires’ disease before installing the copper-silver ionization system. After installation, the Legionella positivity rate (percentage of test sites within the building positive for Legionella) was reduced to 0%. Long-term care facilityThe long-term care facility reported two Legionnaires’ cases before installing the copper-silver ionization system. During the early stages of treatment, instabilities in both copper and silver concentrations occurred and were attributed to electrode scaling. This was followed by an increase in Legionella. Once ion concentrations were stabilized, the Legionella positivity rate was reduced to 0%. ConclusionCopper-silver ionization successfully controlled Legionella under alkaline water conditions but required frequent monitoring and system adjustments to maintain efficacy. The study found that alkaline water conditions reduce copper ion concentrations, however, the facilities were able to achieve non-detect as silver ions were less impacted and appeared to be the main ion controlling Legionella. Full study
