"Responsible Person" is identified in the HSE's Approved Code of Practice & Guidance document L8 as someone with day-to-day responsibility for controlling any identified risk from Legionella bacteria.
The appointed "Responsible Person" should be a manager, or someone of similar status who has sufficient authority, competence and knowledge of the installation to ensure that all operational procedures are carried out in a timely and effective manner. They should also have a clear understanding of their duties and the overall health and safety management structure and policy in the organisation.