A study completed in 1994 with copper and silver water ionisation of a hospital water distribution system found complete inactivation of Legionella pneumophila and L. bozemanii when exposed to 0.4 mg/l copper and 0.04 mg/l silver and continued residual inactivation two months after the copper and silver water ionisation unit was switched off.
Results of tests by BSRIA show that copper and silver water ionisation is clinically proven against Legionella in cold and hot water systems with water temperatures as low as 35°C.
This study also shows that the copper and silver ions not only reduce biofilm coverage in cisterns and within pipework circuits, they also reduce the number of Legionella bacteria present within the biofilm.
Essentially this means copper and silver ionisation is clinically proven to control Legionella and Pseudomonas.
Conclusions from a study carried out in the U.S.A in 1998 by the University of Pittsburgh specify that copper and silver water ionisation for Legionella control outperform conventional treatment techniques. This includes as hyper-chlorination, chlorine dioxide, super-heating and flush, and UV light systems because of the following advantages:
- Installation and maintenance are easy.
- High water temperatures does not affect efficacy (unlike with chlorine dioxide and UV light systems).
- Residual disinfectant protection occurs throughout the system (unlike with UV light).
- Delays re-colonization because the copper and silver ions kill rather than suppress Legionella bacteria (unlike with chlorine dioxide).
A study into the long-term (5 to 11 years) efficacy of copper and silver ionisation for Legionella control in 16 hospital water systems concludes that copper and silver ionization reduces the incidence of hospital-acquired legionnaires disease. It was the only disinfection modality to fulfill all evaluation criteria that the U.S.A. recommend you apply to Legionella control approaches.
ProEconomy have been analyzing water since 1993 and have built up substantial data on results. These show that when silver ion concentrations at outlets are between 0.02 and 0.08 mg/l and copper ion concentrations at outlets are between 0.2 and 0.4 mg/l we can avoid Legionella contamination.
Much more research proving the efficacy of the Orca system is available and Dr Birgitta Bedford (PhD from Cranfield University in Legionella control) has compiled a list of references of over 40 scientific papers that support copper and silver water ionisation.
