Domestic and in-line legionella disinfection

"The piping was flushed with 80 degree water (c)for one hour everyday. This should have solved the problem”.

Although at this temperature legionella bacteria are killed, the so called thermal disinfection is not sufficient to prevent recontamination in the future.

Legionella bacteria in itself are relatively easy to kill. These bacteria however have the possibility to nest themselves inside host organisms, like amoeba or biofilm. This is where thermal disinfection runs into problems. Biofilm is very resistant to most removal treatments, and the thermal treatment is no exception to this. The treatment to remove legionella is often ineffective to remove biofilm and therefore a total removal of the contamination is not possible or just temporarily.

A complete legionella treatment with SCD (stabilised chlorine dioxide) should look like this:

1. Soak the contaminated parts (usually the showerhead) in a 50-100 ppm solution for several minutes. This will remove and kill the legionella and the biofilm.

1. Completely fill up the piping with a 50 ppm solution and soak for one hour.
   After flushing with clean water this will result in a biofilm end legionella free system.

1. Continuous dosing at 0,5 ppm prevents the formation of biofilm and bacteria growth.