American Water Works Association (AWWA), Water Science, March 2023
This 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.
Previous research indicates that copper-silver ionization is effective for Legionella control. Other key findings of this study include:
- Copper and silver can work as biocides independently or together.
- The EPA recognizes both copper and silver as metallic antimicrobial agents.
- Copper-silver ionization is effective against various waterborne pathogens, including Legionella, Nontuberculous Mycobacterium, Pseudomonas, Stenotrophomonas, Acinetobacter, and fungi.
- There is no evidence of copper-silver resistance occurring with Legionella.
- Factors that should be considered during planning, commissioning, and system operation include temperature, oxygen levels in the water, flow, pH levels, biofilm, sediment, and other chemicals.
- Case studies reviewed show positive results for general hospitals, specialty hospitals, children’s hospitals, veterans’ hospitals, multi-family buildings, and hotels.
The 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.