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Stephen Deem, P.E.

Regional Engineer, Washington State Department of Health

Stephen Deem Steve Deem is a professional engineer with over 30 years’ experience in water and sanitation issues. He works for the Office of Drinking Water in Engineering and Technical Services representing the Washington State Department of Health. He is also a consultant and international programs staff for Water 1st International, a non-profit water and sanitation development organization. His experience encompasses settings from Kurdish refugee camps in Northern Iraq to post-war rehabilitation in Bosnia and Herzegovina, and from water and toilets in the slums of Dhaka, Bangladesh to research on ultraviolet light disinfection with the Water Research Foundation. He is a member of the National Blue Ribbon Commission for Onsite Non-potable Water Systems, and recently published an article on Legionella and building water systems in the Journal AWWA. Steve received an M.S. in environmental engineering from the University of Washington and a B.S. in civil engineering from Marquette University.

COVID-19 Guidance for Legionella and Building Water System Closures

Abstract: Many buildings are closed to the public or have limited access to help slow the spread of COVID-19. The resulting drop in building water use increases the risk for the formation of biofilm, which supports Legionella growth in building plumbing and associated equipment like cooling towers, pools, decorative fountains, hot tubs and other equipment. If Legionella grows during low-use periods, building users have a higher risk of contracting Legionnaires’ disease and Pontiac Fever during the shutdown and when full use resumes. To prevent Legionella growth, these systems must be actively managed and maintained. While Legionella is a primary risk, the risk of other opportunistic pathogens (Mycobacterium avium) and metal corrosion concerns (lead scale release) is increased by closure or reduced use.

The Washington State Department of Health (WSDOH) identified this issue as significant in early April 2020. Due to an absence of viable guidance the department created its first version of building guidance on April 27 based largely on efforts originating in the European Union. WSDOH has published three guidance documents on this subject while revising the original document to reflect increased understanding and lessons learned (currently version 5). This presentation provides a brief review of the three guidance documents and touches on some issues/factors the WSDOH believes are key to managing and protecting public health.