Recovery of microbiological quality of long-term stagnant tap water in university buildings during the COVID-19 pandemic

Ye, Chengsong; Xian, Xuanxuan; Bao, Ruihan; Zhang, Yiting; Feng, Mingbao; Lin, Wenfang; Yu, Xin

doi:10.1016/j.scitotenv.2021.150616

Cited by 26 publications

(32 citation statements)

References 39 publications

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“…Ye et al reported the recovery of water quality parameters in university buildings after being unoccupied for 5 months. As the building returned to normal water demand, the occurrence rate and concentration of L. pneumophila did not decrease as expected if the closure resulted in growth [ 32 ]. De Giglio et al reported that sample positivity rate did not consistently increase during 3-month closures, but levels of culturable L. pneumophila increased in all three wards monitored by a median of 175 to 5525 CFU/L [ 33 ].…”

Section: Discussionmentioning

confidence: 99%

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

et al. 2022

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When stay-at-home orders were issued to slow the spread of COVID-19, building occupancy (and water demand) was drastically decreased in many buildings. There was concern that widespread low water demand may cause unprecedented Legionella occurrence and Legionnaires’ disease incidence. In lieu of evidenced-based guidance, many people flushed their water systems as a preventative measure, using highly variable practices. Here, we present field-scale research from a building before, during, and after periods of low occupancy, and controlled stagnation experiments. We document no change, a > 4-log increase, and a > 1.5-log decrease of L. pneumophila during 3- to 7-week periods of low water demand. L. pneumophila increased by > 1-log after precautionary flushing prior to reoccupancy, which was repeated in controlled boiler flushing experiments. These results demonstrate that the impact of low water demand (colloquially called stagnation) is not as straight forward as is generally assumed, and that some flushing practices have potential unintended consequences. In particular, stagnation must be considered in context with other Legionella growth factors like temperature and flow profiles. Boiler flushing practices that dramatically increase the flow rate and rapidly deplete boiler temperature may mobilize Legionella present in biofilms and sediment.

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Section: Discussionmentioning

confidence: 99%

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

et al. 2022

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“…33 Recent investigations into the impact of COVID-19 pandemic building closures have reported that building water quality overall was negatively impacted. 7,[44][45][46][47][48][49] However, studies have reported mixed results with respect to L. pneumophila, including no detection of L. pneumophila, 44,49 no change in occurrence as water use returned to normal levels, 45 a small increase (2x) in Legionella spp. relative abundance after two months of reduced water use, 47 and widespread detection of L. pneumophila that increased during closure.…”

Section: Introductionmentioning

confidence: 99%

Legionella pneumophilaoccurrence in reduced-occupancy buildings in 11 cities during the COVID-19 pandemic

Dowdell

Greenwald

Joshi

et al. 2022

Preprint

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In spring 2020, reduced water demand was an unintended consequence of COVID-19 pandemic-related building closures. Concerns arose that contaminants associated with water stagnation, such as Legionella pneumophila, could become prevalent. To investigate this potential public health risk, samples from 26 reduced-occupancy buildings across 11 cities in the United States, Canada, and Switzerland were analyzed for L. pneumophila using liquid culture (Legiolert, n=258) and DNA-based methods (qPCR/ddPCR, n=138). L. pneumophila culture-positivity was largely associated with just five buildings, each of which had specific design or operational deficiencies commonly associated with L. pneumophila occurrence. Samples from free chlorine buildings had higher culture-positivity (37%) than chloramine buildings (1%), and 78% of culture-positive samples occurred when the residual was ≤0.1 mg/L Cl2. Although overall sample positivities using culture- and DNA-based methods were equivalent (34% vs. 35%), there was disagreement between the methods in 13% of paired samples. Few buildings reported any water management activities, and L. pneumophila concentrations in flushed samples were occasionally greater than in first-draw samples. This study provides insight into how building plumbing characteristics and management practices contribute to L. pneumophila occurrence during low water use periods and can inform targeted prevention and mitigation efforts.

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“…During the temporary building closures due to COVID-19, the water tank of the buildings are likely to have microbiological contaminants [109], which may take a long period to recover to the normal levels. Furthermore, increased legionella [110] can cause health hazards for the building's occupants.…”

Section: Water and Sanitary System Safetymentioning

confidence: 99%

“…During COVID-19 temporary building closure, routine flushing and shock disinfection were indicated as possible microbiological and legionella risk control methods [109].…”

mentioning

confidence: 99%

COVID-19 Experience Transforming the Protective Environment of Office Buildings and Spaces

2021

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The COVID-19 pandemic has affected human life in every possible way and, alongside this, the need has been felt that office buildings and workplaces must have protective and preventive layers against COVID-19 transmission so that a smooth transition from ‘work from home’ to ‘work from office’ is possible. However, a comprehensive understanding of how the protective environment can be built around office buildings and workspaces, based on the year-long experience of living with COVID-19, is largely absent. The present study reviews international agency regulation, country regulation, updated journal articles, etc., to critically understand lessons learned from the COVID-19 pandemic and evaluate the expected changes in sustainability requirements of office buildings and workplaces. The built environment, control environment, and regulatory environment around office buildings and workplaces have been put under test on safety grounds during the pandemic. Workers switched over to safely work from home. Our findings bring out the changes required to be affected in the three broad environmental dimensions to limit their vulnerability status experienced during the pandemic. Office building designs should be fundamentally oriented to provide certain safety protective measures to the workers, such as touch-free technologies, open working layouts, and workplace flexibilities to diminish the probability of getting infected. Engineering and administrative control mechanisms should work in a complementary way to eliminate the risk of disease spread. Country regulation, agency regulations, and operational guidelines need to bring behavioral changes required to protect workers from the COVID-19 pandemic.

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Recovery of microbiological quality of long-term stagnant tap water in university buildings during the COVID-19 pandemic

Cited by 26 publications

References 39 publications

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

Variable Legionella Response to Building Occupancy Patterns and Precautionary Flushing

Legionella pneumophilaoccurrence in reduced-occupancy buildings in 11 cities during the COVID-19 pandemic

COVID-19 Experience Transforming the Protective Environment of Office Buildings and Spaces

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