Home\WateReuse Pacific Northwest\How Prevalent is Legionella in Recycled Water?

How Prevalent is Legionella in Recycled Water?

February 18, 2016 @ 12:00 pm – 1:00 pm

Webcast – Presented by WateReuse Pacific Northwest and the WateReuse Research Foundation
12:00 p.m. – 1 p.m. PST
3:00 p.m. – 4:00 p.m. EST
PDHs: 1
Fee: Free for Association and Foundation members

Legionella have a ubiquitous occurrence in diverse water environments including water systems where their presence could be an issue because human infections may be acquired through inhalation of contaminated droplets. 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 including Acanthamoeba, Naegleria and Hartmenella can serve as hosts and reservoirs of Legionella bacteria in reclaimed water systems.

The current WateReuse Research Foundation project (12-05) is designed to assess the occurrence of Legionella following conventional and advanced treatment processes, understand the impact of commonly used disinfectants on the viability of Legionella and associated amoebae in matrices of varying water quality, and utilize advanced methodologies to characterize the Legionella species and serogroups detected. The project will develop best management practices (BMPs) to minimize the occurrence and/or concentrations of Legionella in water systems.

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 and best management practices will be summarized. The results of this project will be valuable in proactively addressing and mitigating potential risks from Legionella in drinking water and reclaimed water and will benefit water utilities, scientists, and public health regulators


Dr. Mark W. LeChevallier is currently the Director of Innovation & Environmental Stewardship at the American Water Corporate Center in Voorhees, NJ. In this capacity he directs a staff of about 40 for both the research and environmental compliance programs. Research areas have included bacterial regrowth, disinfection of biofilms, corrosion, bacterial nutrients, AOC measurement techniques, biological treatment, Mycobacterium, microbial recovery and identification, modeling and impact of pressure transients on water quality, and detection, treatment and survival of Giardia and Cryptosporidium.

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