B4: The Chicken or the Egg of Legionella and Public Water Supplies

John Springston, CIH, CSP, FAIHA Moderator
ATC Group Services
United States of America
Dr. J. David Krause, PhD, CIh Presenter
Tallahassee, FL 
United States of America
Dr. Janet Stout, PhD Co-Presenter
Special Pathogens Lab
Pittsburgh, PA 
United States of America
Mon, 5/24: 11:15 AM - 12:15 PM
Education Session 
Room: Virtual 4 


Legionella colonization of building water systems can be influenced by the quality of incoming water and the presence of Legionella. The microbiology of building water systems can be influenced by municipal water systems. Water quality, disinfectant levels, and the presence of Legionella at low levels in municipal water can determine whether Legionella or other waterborne pathogens colonize, grow, and spread in building water systems. This session will present the following topics: 1) does incoming water quality and chemistry (the egg) predict the presence or absence of Legionella growth in building water systems (the chicken); 2) what Legionella risks occur when occupying buildings have sat unused or operated at reduced capacity due to COVID restrictions; 3) recommended assessments and actions for building water systems; and 4) update on industry guidelines, including the AIHA Guideline and Body of Knowledge.

Learning Outcomes

Upon completion of the session, the participant will be able to:

• Recognize the influence of incoming water on Legionella contamination.
• Identify the types of bacteria found in water systems.
• Utilize the appropriate methods for testing and assessing risk.
• Determine the relationship between water quality and Legionella.
• Use the AIHA Body of Knowledge on Legionella. 

Content Level


Interactive Session Experience



Available as part of AIHce OnDemand
Hazard Recognition/Exposure Assessment
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