Water quality challenges in buildings during prolonged low or no occupancy: a cause for concern during COVID-19 lockdowns and related building closures

ABSTRACT

Introduction: In compliance with the COVID-19 lockdown restrictions, many nonessential workplaces and public spaces were closed or left sub-operational with no or low occupancy for several months. The abrupt and unprecedented long periods of building closures have raised concerns about the proliferation of opportunistic premise plumbing pathogens that may be a biohazard for returning occupants. Objective: In this review paper, we discuss microbiological water quality concerns during periods of no or low occupancy, as experienced during the COVID-19 lockdowns. Methods: PubMed and Google Scholar databases were searched for peer-reviewed articles using specific keywords. The literature search was extended to grey literature. The paper focuses on Legionella, as a pathogen of concern, in building water systems that are not well managed and the potential risks to workers and other occupants. Results: Most articles suggest a positive relationship between stagnation or reduced water usage and compromised microbiological quality of building water systems, but the effects are site-specific and are associated with biofilm formation and disinfectant decline. Considerations for building water risk assessment are discussed as a decision-making framework for selecting appropriate responses to anticipated changes in water quality. Conclusion: The unprecedented building closures due to COVID-19 lockdowns present a hazardous event likely to impact building water quality. Building owners and facility managers, especially in high-risk settings, should consider conducting risk assessments of water systems during low-occupancy periods to identify potential risks and apply appropriate corrective measures, where necessary.