Zeming Liu, Janet E. Stout, Lou Tedesco, Marcia Bolding, Charles Hwang, Warren F. Diven, Victor L. Yu
The University of Chicago Press, The Journal of Infectious Diseases, April 1994
This study evaluated the efficacy of copper-silver ionization in a hospital with active Legionella colonization after superheat-and-flush and hyperchlorination had proven ineffective.
Six months after installation, the Legionella positivity rate (percentage of test sites within the building positive for Legionella) dropped significantly in the test building.
- Test building: Legionella positivity rate reduced from 50% to 0.8% after six months
- Control building (no copper-silver ionization): Mean positivity rate of 67% for study duration
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.
Copper-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.