TITLE: Development of a Risk Management Strategy for Legionella in Drinking Water

About This Training Event


June 23, 2021 • 11 a.m. – Noon CST


Virtual (GoToWebinar)

Course Description

Legionnaires’ disease, the illness primarily caused by Legionella pneumophila, has increased by over 500% since 2000 and has become the most commonly identified cause of drinking water outbreaks in the U.S.   During the 2013-2014 reporting period, Legionella infections were responsible for all reported deaths due to drinking water-associated illnesses. Presently approximately 60 species consisting of about 70 serogroups of Legionella are known, with some serotypes primarily associated with severe (Legionnaire’s disease) or the self-limiting mild (Pontiac fever) forms of human disease. Although outbreaks are typically associated with the plumbing systems of large buildings and cooling towers, most Legionella cases are not associated with outbreaks. 

Drinking water and reclaimed water distribution systems have been shown to be reservoirs for Legionella.  Factors contributing to Legionella growth include elevated ambient temperatures, scale and sediment accumulation, corrosion, absence of disinfectant residuals, and presence of biodegradable and assimilable organic carbon (i.e. BDOC and AOC).  Free-living amoebae serve as hosts and reservoirs of Legionella bacteria in water systems, so understand the ecology of these organisms is important in the management of Legionella in water.

The presentation will give an overview of the Legionella organisms, occurrence in water, factors contributing to growth and survival, sensitivity to disinfection, and their relationship to free-living amoebae.  Factors contributing to increased risk, as well as best management practices, will be summarized.  Guidance has been developed to help proactively address and mitigate potential risks from Legionella in drinking water and reclaimed water.  The training session will end with a series of recommendations for utility communication with commercial and industrial customers.

Registration Fee

Free for AWWA members (use code AWWAMEMBER)
$10 for nonmembers


This session will be eligible for 1.0 PDH/CEU credit (MDNR Course #2108759)

REGISTER ONLINE pdfDownload Info Sheet


M ark LeChevallier

Mark LeChevallier, PhD
Principal and Manager at Dr. Water Consulting LLC

Dr. Mark LeChevallier is the principal and manager of Dr. Water Consulting LLC, a part-time consulting business, after retiring from American Water at the end of 2017. Dr. LeChevallier received his Bachelor of Science and Master’s degrees in Microbiology from Oregon State University, and his Ph.D. in Microbiology from Montana State University. Dr. LeChevallier has authored over 300 research papers and has received numerous awards for his research.  He currently serves on the Drinking Water subcommittee of the USEPA Science Advisory Board, the Water Science & Technology Board for the National Academy of Science, and was a member of the NAS Legionella workgroup. He is a fellow of the American Academy of Microbiology.
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