Hi Kevin Do you actually have an outbreak of Legionnaires Disease or have you discovered the presence of the legionellosis bacteria? The former is quite serious - requires hospitalisation and is, I believe, a notifiable disease. The latter can be dealt with by getting a specialist in to clean and neutralise your water supplies/storage and you can find one by using the Google search engine. Regards Hils

Hi Kevin, You will need your system cleaning professionally and then you will need to carry out a risk assessment (or, preferably, pay an expert to do one for you) and follow the recommendations to prevent it coming back. These will include temperature control and possibly changes to your system, John

Kevin, you will never eradicate it! Your water supplier sends it you "free of charge", then you need to control it? Download a copy of the ACOP and get some help from someone who understands Legionella and whichever water system you have.