Are you keeping up to date with British Standards? see
BS 8580-1:2019 Water Quality Risk Assessments For Legionella Control. Code Of Practice (British Standard)
BS 8580-2. 2022 Water quality - Part 2. Risk assessments for Pseudomonas aeruginosa and other waterborne pathogens. Code of practice
BS 7592:2022 . Sampling for Legionella bacteria in water systems. Code of practice
BS 8680:2020 Water quality. Water safety plans. Code of practice