Project #5033

Demonstrating the Effectiveness of Flushing for Reducing the Levels of Legionella in Service Lines and Premise Plumbing

Principal Investigator
Research Manager
Hyunyoung Jang, PhD
Norwegian University of Science & Technology
Microbes & Pathogens
Opportunistic Pathogens
Water Quality


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. Flushing is a common approach used to control Legionella levels in building plumbing systems, but there are no standard or widely accepted approaches. This project assessed 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 pilot and field studies, the project team provided evidence-based recommendations for building managers, making it accessible and practical for real-world application. A framework (chapter 7) and fact sheet (see the project paper) provide recommendations and flushing procedure based on the research findings. Published in 2024.