Improved design and operations of building water systems to reduce health risks caused by water & energy conservation and extended shutdowns

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Stagnation of water in building water systems can cause elevated concentrations of toxic metals and pathogens such as Legionella pneumophila, Pseudomonas aeruginosa and Non Tuberculus Mycobacteria. Pathogens can be amplified within building water systems and cause outbreaks and community acquired disease. Legionella is now the most common cause of drinking water associated outbreaks and Legionnaire's disease rates are increasing rapidly. Maintaining water quality in buildings is a growing challenge because of the unintended consequences of water and energy conservations measures that have been shown to increase health risks. Such measures are highly justified but have unfortunately been implemented to legacy building systems without regard for water quality, often causing severe water quality losses. Recently, the SARS-CoV-2 global pandemic forced extended closures of a staggering number of buildings across Canada with extreme stagnation causing unsafe water. The research program aims to provide the evidence to base recommendations to improve the design and operations of building water systems and ensure the provision of safe water. The widespread implementation of low flow devices and thermostatic valves impacts water quality building in water systems. Energy conservation measures for hot water systems in large buildings such as heat exchangers, lowering of temperature set points have led to the proliferation of Legionella causing documented cases and fatalities in Canadian health care facilities. The consequences of these conservation measures is poorly documented and need to be quantified. The research program will address the key knowledge gaps through a combination of field investigations, pilot and bench scale assays, laboratory studies, risk analysis and regulatory impact investigations. Field studies will document the prevalence of pathogens, microbial diversity and the presence of toxic metals in building water systems across Canada using innovative sampling strategies. Intervention field studies will document the impacts of commissioning procedures and water conservation retrofits. Pilot studies will focus on the interplay between materials, water quality and water usage. Laboratory and bench-scale studies will quantify the production of aerosols and colonization potential of low flow faucets and showers to quantify the exposure pathways. Risk analysis (QMRA) models will be used to guide the selection of alert and action levels and define optimal regulatory frameworks. Research results will provide actionable evidence to reduce health risks to their occupants and will be conducted in close collaboration with utilities, regulators and associations with the clear intent of providing: a basis for streamlined and effective guidance and regulations, cost effective environmental monitoring programs, modifications of the building code, drinking water compatible material certification and reviewed building water system design approaches.