After reviewing the sample reports it was found that the sample had been taken from areas that were not used by customers. And were not impacting the dental lines which were supplied by reverse osmosis water purchased in drums and not filtered at the premises. This significantly reduced the risk of exposure to legionnaires disease.
The positive sample results were found on instant water heaters in all practices, as they were found faulty and infrequently used. This meant that the sample results were isolated.