Microbiological Evaluation of Copper : Silver Disinfection Units for Use in Swimming Pools

Abstract

The bactericidal effects of electrolytically generated copper:silver ions on pathogenic bacteria of concern in swimming pools, hot tubs and cooling towers were evaluated in disinfection experiments. Copper:silver ion concentrations generated in well water were 400:40 µg/L, respectively. Pure cultures of Legionellapneumophila, Staphylococcusaureus, Pseudomonasaeruginosa, Escherichiacoli, and Streptococcusfaecalis, were individually tested in water containing copper:silver ions alone, copper:silver ions with free chlorine, and free chlorine alone. Greater numbers of organisms were killed after exposure to copper: silver ions with 0.2 mg/L free chlorine than in either the copper:silver ions or free chlorine alone. L. pneumophlla showed greater than a 5 log10 reduction in numbers after 7 minutes exposure to copper:silver ions with 0.2 mg/L free chlorine. In comparison, less than a 2 log10 decrease was obtained after exposure to free chlorine alone. E.coli numbers decreased over 4 log10 after 1 minute exposure to copper:silver ions with 0.2 mg/L free chlorine and less than a 3 log10 decrease after exposure to free chlorine alone. The majority of the other organisms tested showed the same effect. Electrolytically generated copper:silver ions with low levels of free chlorine appear to have greater bactericidal activities than either disinfectant alone.