Temperature diagnostic to identify high risk areas and optimize Legionella pneumophila surveillance in hot water distribution systems.

Emilie Bédard 1, 2, * Stéphanie Fey 1 Dominique Charron 1 Cindy Lalancette 2 Philippe Cantin 3 Patrick Dolcé 4 Céline Laferrière 5 Eric Déziel 2 Michèle Prévost 1
* Corresponding author
1 École Polytechinique, département de génie civil
2 INRS-IAF - Institut Armand Frappier
3 CEAEQ - Centre d'Expertise en Analyse Environnementale du Quebec
4 Centre Hospitalier Régional de Rimouski
5 CHU Sainte Justine [Montréal]
Abstract : Legionella pneumophila is frequently detected in hot water distribution systems and thermal control is a common measure implemented by health care facilities. A risk assessment based on water temperature profiling and temperature distribution within the network is proposed, to guide effective monitoring strategies and allow the identification of high risk areas. Temperature and heat loss at control points (water heater, recirculation, representative points-of-use) were monitored in various sections of five health care facilities hot water distribution systems and results used to develop a temperature-based risk assessment tool. Detailed investigations show that defective return valves in faucets can cause widespread temperature losses because of hot and cold water mixing. Systems in which water temperature coming out of the water heaters was kept consistently above 60 °C and maintained above 55 °C across the network were negative for Legionella by culture or qPCR. For systems not meeting these temperature criteria, risk areas for L. pneumophila were identified using temperature profiling and system's characterization; higher risk was confirmed by more frequent microbiological detection by culture and qPCR. Results confirmed that maintaining sufficiently high temperatures within hot water distribution systems suppressed L. pneumophila culturability. However, the risk remains as shown by the persistence of L. pneumophila by qPCR.
Keywords : Thermal control Premise plumbing Temperature profile Culturability Legionella pneumophila Viable but not culturable (VBNC)
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Journal articles
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https://hal-riip.archives-ouvertes.fr/pasteur-01351894
Contributor : Michel Courcelles <>
Submitted on : Thursday, August 4, 2016 - 8:08:39 PM
Last modification on : Monday, October 8, 2018 - 5:44:05 PM

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Emilie Bédard, Stéphanie Fey, Dominique Charron, Cindy Lalancette, Philippe Cantin, et al.. Temperature diagnostic to identify high risk areas and optimize Legionella pneumophila surveillance in hot water distribution systems.. Water Research, IWA Publishing, 2015, 71, pp.244-56. ⟨10.1016/j.watres.2015.01.006⟩. ⟨pasteur-01351894⟩

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