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
Intermittent Use of Copper-Silver Ionization for Legionella Control in Water Distribution Systems: A Potential Option in Buildings Housing Individuals at Low Risk of Infection
ZEMING LIU, JANET E. STOUT, MARCIE BOLDIN, JOHN RUGH, WARREN F. DIVEN, VICTOR L. YUOXFORD ACADEMIC, CLINICAL INFECTIOUS DISEASES, JANUARY 1998 IntroductionThis study evaluated three healthcare facilities colonized with Legionella to determine if: ResultsThe Legionella positivity rate (percentage of test sites positive for Legionella) was significantly reduced for the two test buildings using copper-silver ionization. Both test buildings remained Legionella-free for six to eight weeks after deactivating the copper-silver ionization system. The researchers found high concentrations of copper in the biofilm and suggested this to be the reason that early recolonization of Legionella was prevented. ConclusionBecause copper-silver ionization provides a residual effect of preventing early recolonization of Legionella, it is possible to rotate one copper-silver unit between several buildings. The study explained that this method could be considered for facilities that house individuals at low risk for contracting Legionnaires’ disease. Full study
Experiences of the First 16 Hospitals Using Copper-Silver Ionization for Legionella Control: Implications for the Evaluation of Other Disinfection Modalities
JANET E. STOUT, VICTOR L. YUCAMBRIDGE UNIVERSITY PRESS, INFECTION CONTROL AND HOSPITAL EPIDEMIOLOGY, AUGUST 2003 IntroductionThis study examined 16 acute care hospitals using copper-silver ionization as a disinfection method. Surveys were deployed in 1995 and 2000 to gather information from each hospital. The 2000 survey was up to 11 years after installation for some hospitals. ResultsBefore installing a copper-silver ionization system, all 16 hospitals had reported cases of hospital-acquired Legionnaires’ disease. Seventy-five percent had tried other disinfection methods, including superheat-and-flush, ultraviolet light, and hyperchlorination. After installing a copper-silver ionization system, no cases of hospital-acquired Legionnaires’ disease were reported, and the Legionella positivity rate (percentage of test sites within the hospital positive for Legionella) was significantly reduced. The study found that the infection control practitioners rated the disinfection system as “excellent.” The engineers rated the operation and maintenance of the system as “average” (not easy, but also not difficult). ConclusionThe team behind this study developed a standardized, evidence-based approach to assist hospitals with evaluating different disinfection methods. The four criteria a disinfection method must meet include the following: At the time of this study, copper-silver ionization was the only disinfection modality to have fulfilled all four evaluation criteria. Full study
Controlled Evaluation of Copper-Silver Ionization in Eradicating Legionella pneumophila from a Hospital Water Distribution System
ZEMING LIU, JANET E. STOUT, LOU TEDESCO, MARCIA BOLDING, CHARLES HWANG, WARREN F. DIVEN, VICTOR L. YUTHE UNIVERSITY OF CHICAGO PRESS, THE JOURNAL OF INFECTIOUS DISEASES, APRIL 1994 IntroductionThis study evaluated the efficacy of copper-silver ionization in a hospital with active Legionella colonization after superheat-and-flush and hyperchlorination had proven ineffective. ResultsSix months after installation, the Legionella positivity rate (percentage of test sites within the building positive for Legionella) dropped significantly in the test building. The copper-silver ionization systems were turned off to assess the length of time before Legionella recolonization. The test building remained negative for two months, with only one of the 26 test sites showing Legionella after four months. The control building remained positive. ConclusionCopper-silver ionization successfully eliminated Legionella in the hospital’s water system. The advantages of copper-silver ionization include relatively low cost, straightforward installation, easy maintenance, nontoxic by-products, and the presence of a disinfecting residual. Full study
Controlling Legionella in Hospital Water Systems: Experience With the Superheat-and-Flush Method and Copper-Silver Ionization
JANET E. STOUT, YU-SEN E. LIN, ANGELLA M. GOETZ, ROBERT R. MUDERCAMBRIDGE UNIVERSITY PRESS, INFECTION CONTROL AND HOSPITAL EPIDEMIOLOGY, DECEMBER 1998 IntroductionThis study evaluated the efficacy of superheat-and-flush and copper-silver ionization for Legionella control in an acute care hospital. The hospital had been using the superheat-and-flush method for 13 years but was still experiencing incidences of Legionnaires’ disease. ResultsLegionnaires’ cases decreased once the copper-silver ionization system was installed, with no cases reported in the last year evaluated by the study (1997). The average number of Legionnaires’ cases from 1979 to 1996 are included below. ConclusionCopper-silver ionization was found to be more effective in controlling Legionella than superheat-and-flush. The study notes that hospitals must conduct routine Legionella testing and closely monitor ion concentrations for copper-silver ionization to remain effective. Full study
Controlling Legionella pneumophila in Water Systems at Reduced Hot Water Temperatures with Copper and Silver Ionization
ELAINE CLOUTMAN-GREEN, VERA L BARBOSA, DIEGO JIMENEZ, DANIEL WONG, HELEN DUNN, BRIAN NEEDHAM, LENA CIRIC, JOHN C HARTLEYELSEVIER, AMERICAN JOURNAL OF INFECTION CONTROL, JANUARY 2019 IntroductionThis study was conducted at a newly built healthcare facility in the United Kingdom. There, the Department of Health recommends maintaining hot water temperatures above 131o F (55o C) to control Legionella in water supply systems. The goal of this study was to determine the efficacy of copper-silver ionization to control Legionella at deliberately reduced hot water temperatures in a newly-constructed healthcare facility. ResultsThe results of routine monthly sampling (1,598 total) from 2011 to 2017 demonstrated effective (100%) Legionella control with an average hot water temperature of 107.6°F (42°C). The facility experienced a 33% reduction in energy usage and a 24% reduction in carbon emissions. ConclusionThis study showed that the spread of Legionella could be controlled at reduced hot water temperatures, but interventions were required to maintain adequate levels of copper and silver. 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
Controlling Legionella Case Study: Chlorine Dioxide vs. Copper-Silver Ionization
In 2009, an outbreak of Legionnaire’s Disease hit a large Georgia hospital, affecting six wards, and resulting in the closure of 10% of their patient beds. After trying several solutions, including installation of continuous chlorine dioxide systems and plumbing infrastructure upgrades, the hospital still tested positive for Legionella. In 2023, the hospital partnered with LiquiTech to install a LiquiTech™ Copper-Silver Ionization System to control the Legionella contamination and reduce the risk of future disease outbreaks. Within just two months of installing copper-silver ionization, the Legionella positivity rate dropped from 100% to 11%, with the next round of testing showing 0% positivity. Through its ongoing service partnership with LiquiTech, the hospital has successfully maintained control of the Legionella contamination. By choosing the right technology and ensuring ongoing maintenance, the hospital’s priorities of protecting their staff and patients and controlling waterborne pathogens were achieved. To learn more, read the full case study here.
News Release: New Study Shows Copper-Silver Ionization is Effective for Legionella Control
Legionnaires’ disease cases have increased nearly tenfold in recent decades, leading to thousands of hospitalizations and deaths. Outbreaks are linked to Legionella, a bacteria found in potable water systems in large facilities like hospitals, multi-family buildings, resorts, and office buildings. A recently published study shows that copper-silver ionization effectively controls Legionella in building water systems to prevent Legionnaires’ disease. A new study published in the American Water Works Association (AWWA) Water Science journal shows that copper-silver ionization effectively controls Legionella in building water systems. The study, conducted by Dr. Mark LeChevallier with technical and financial support from LiquiTech, examines more than 80 sources of research studies and related literature to analyze the efficacy of copper-silver ionization as a water treatment solution. Dr. LeChevallier concludes “that use of copper-silver ionization to control Legionella and other opportunistic pathogens is highly effective when the units are properly designed, maintained, and operated.” Legionnaires’ disease cases have increased nearly tenfold in recent decades, leading to thousands of hospitalizations. Those who catch Legionnaires’ disease experience a severe form of pneumonia caused by Legionella, a bacteria found in poorly maintained water systems. Studies show that Legionella is responsible for about two-thirds of all disease outbreaks from drinking water and the cause of all documented deaths attributed to drinking water-associated infections. Historically, outbreaks were linked to cooling tower systems. As our understanding of Legionella has advanced over recent decades, most outbreaks are now connected to potable water systems in large facilities, such as hospitals, long-term healthcare facilities, resorts, and office buildings. It’s estimated that 54% of all potable building water systems have some level of Legionella present. Plumbing codes and regulations have been developed to standardize the design, structure, and management of building water systems to prevent waterborne diseases. However, based on the studies cited in this article and elsewhere, there is a need for supplemental treatment of building water systems. One such supplemental treatment is copper-silver ionization, a chemical-free disinfection solution for potable water systems. It releases copper and silver ions into the building’s water system to destroy waterborne pathogens like Legionella. Copper-silver ionization is not a new water treatment option. Silver ionization was used in the 1960s by NASA for the sanitation of water on spacecraft. In the 1980s, copper-silver ionization was used in swimming pools as an alternative to chlorine. Later, in 1994, copper-silver ionization was the first reported effective treatment for controlling Legionella in a hospital. Today, copper-silver ionization is used to prevent waterborne pathogens in a variety of buildings with complex water systems. Although copper-silver ionization is a low-cost and chemical-free option for water disinfection, the system must be designed properly and used in the appropriate applications to achieve optimal results. Crucial to its effectiveness is identifying and responding to abnormalities in water usage patterns and chemistry. Dr. LeChevallier, a drinking water research scientist with a Ph.D. in Microbiology, examined literature and studies related to copper-silver ionization system design, maintenance, and operations, and the impact water chemistry has on its performance. In addition to authoring more than 300 research papers, Dr. LeChevallier is a member of the Drinking Water Subcommittee of the Science Advisory Board of the United States Environmental Protection Agency (US EPA), a past member of the Water Science Technology Board of the National Academies of Science, and the past Chair of the AWWA Water Science & Research Division. In his recently published study, Dr. LeChevallier explained, “These water quality and operational characteristics must be properly addressed to assure that the highest disinfection efficacy is obtained through copper-silver ionization.” He reviewed research and related literature to investigate the mechanisms of copper and silver disinfection. Copper-silver ionization works by treating water through electrolysis. An electric current is applied to a copper and silver bar to produce and release positively charged ions. These copper and silver ions then find microorganisms in the water with a negative charge, like Legionella. The copper ions bond to the negative walls of the microorganisms, disrupting cell wall permeability and the absorption of life-sustaining nutrients. This disruption to the cell wall allows the silver ions to enter and destroy the core of the bacteria, thus making it impossible to survive. Dr. LeChevallier cited studies showing that copper and silver can work as biocides independently or together. One study emphasized that combined treatment with copper and silver was associated with decreased incidence of Legionella and a faster reduction of bacteria than copper or silver alone. In addition to copper-silver ionization being considered an effective supplemental method for water treatment by researchers, the US EPA has recognized both copper and silver as metallic antimicrobial agents. Studies show that copper-silver ionization is effective against many waterborne pathogens, including Legionella, Nontuberculous Mycobacterium, Pseudomonas, Stenotrophomonas, Acinetobacter, and fungi. While the issue of copper-silver resistance was discussed in portions of the literature that Dr. LeChevallier reviewed, it’s important to note that there was no evidence of it occurring with Legionella. Copper-silver resistance, where pathogens can continue to grow and thrive even in the presence of copper and silver, was only observed with E. coli and Salmonella. During his investigation, Dr. LeChevallier found that the design, operation, and maintenance of copper-silver ionization systems are critical to their effective functionality. In his published paper, he explained that copper-silver ionization will act as a water disinfectant; however, the proper engineering and operation of the system are integral to its success. Essential components of the copper-silver ionization system include the electrodes, flow cells, power supply, control panel, flow meter, and web interface. Each component must be operated and maintained for copper-silver ionization to be most effective. “Buyers of [copper-silver ionization] systems should pay attention to the design and configuration of the electrodes – particularly as they wear. The construction of the flow cell and the adequacy of the power supply are important to deliver the necessary amperage to achieve the target copper and silver concentrations. Copper and silver doses should be flow paced and can be remotely monitored with a web-based interface,” said Dr. LeChevallier. Additionally, Dr. LeChevallier cautioned that water quality can impact copper-silver ionization as a water treatment. He explained that water chemistry, physiochemical, and environmental factors can influence the efficacy of copper-silver ionization if not considered and managed correctly. Specific factors to
