Legionella are pervasive environmental bacteria that can incidentally cause severe and sometimes fatal infections upon inhalation. Because Legionella inhabit engineered environments and proliferate in warm, stagnant premise water systems, the majority of outbreaks are associated with preventable water system maintenance deficiencies. This project will assess the use of flushing as a corrective action and ongoing control strategy to reduce Legionella levels in service lines and premise water systems. Using a combination of laboratory experiments and real-world case studies to generate novel, hypothesis-driven data, evidence-based guidance will be provided for a broad audience of potential stakeholders regarding the efficacy of flushing for Legionella control. The guidance documents will provide practical recommendations, including measurable goals and potential costs, based on evidence produced in the laboratory and in the field.