Copper and silver ionisation is clinically proven

Copper and silver ionisation has been clinially proven to be effective for Legionella control by numerous water treatment studies.


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 carried out during a research project completed in 1996 by BSRIA in the UK showed that copper and silver water ionisation was effective against Legionella bacteria in both cold and hot water systems with reduced water temperatures as low as 35°C.

  • This study also showed 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.

Conclusions from a study carried out in the U.S.A in 1998 by the University of Pittsburgh specified that copper and silver water ionisation for Legionella control outperformed conventional treatment techniques such as hyper-chlorination, chlorine dioxide, superheating and flush, and UV light systems because of the following advantages:

  1. installation and maintenance are easy. 
  2. efficacy is not affected by high water temperatures (unlike with chlorine dioxide and UV light systems). 
  3. residual disinfectant protection occurs throughout the system (unlike with UV light). 
  4. re-colonization is delayed 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 concluded that copper and silver ionization reduced the incidence of hospital-acquired legionnaires disease and was the only disinfection modality to have fulfilled all evaluation criteria that the U.S.A. recommend to be applied to Legionella control approaches.

ProEconomy have been analyzing water since 1993 and have built up substantial data on results that shows that when silver ion concentrations at outlets are maintained between 0.02 and 0.08 mg/l and copper ion concentrations at outlets are maintained between 0.2 and 0.4 mg/l Legionella contamination is avoided.

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.

Scientific papers are available upon request.