Characterizing the premise plumbing microbiome in both water and biofilms of a 50-year-old building

Huang, Casey; Weerasekara, Anjani; Bond, Philip; Weynberg, Karen D.; Guo, Jianhua

doi:10.1016/j.scitotenv.2021.149225

Cited by 18 publications

(11 citation statements)

References 38 publications

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“…Previous building water microbiome studies have suggested that bacterial growth through stagnation (Vosloo et al, 2022) and low-flow conditions on copper pipes (Lu et al, 2014) reduces alpha diversity, as was observed in this study. As shear forces dissipated, bulk communities may have become more similar to the biofilm, which has lower diversity than bulk water (Huang et al, 2021) and decreases in diversity through repeated flushing (Douterelo et al, 2016). Under stagnant conditions, biofilm has been shown to become more loosely attached (Liu and Tay, 2002).…”

Section: The Building Water Microbiome During Reduced Water Use and F...mentioning

confidence: 99%

Is flushing necessary during building closures? A study of water quality and bacterial communities during extended reductions in building occupancy

et al. 2022

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Drinking water stagnation can lead to degradation of chlorine residual, bacterial growth (including of opportunistic pathogens and nitrifiers), and metals release from plumbing materials; however, few studies have characterized building water quality and bacterial communities during the extended stagnation periods that occurred during COVID-19 pandemic-related building closures. Additionally, despite a lack of evidence-based guidance, flushing fixtures has been recommended to restore building water quality. We aimed to evaluate the impacts of reduced building occupancy (>2 months) and weekly restorative flushing on drinking water quality, bacterial communities, and the occurrence of undesirable microorganisms in three university buildings. Reduced occupancy led to diminished chloramine and elevated intact cell counts, but values remained stable after additional weeks of limited water use. Flushing temporarily improved water quality, with chlorine and cell counts remaining stable for at least 1 day but returning to levels measured prior to flushing within 1 week. Alpha diversity was lower under more stagnant conditions, and fixture identity, not flushing, was the most influential factor on bacterial community composition, suggesting a strong influence from local biofilm. Although Mycobacterium, Legionella, Pseudomonas, Nitrosomonas, and Nitrospira were detected in samples via amplicon sequencing, concentrations measured via qPCR of M. avium complex, L. pneumophila, P. aeruginosa, and ammonia-oxidizing bacteria were very low or were undetected, supporting that stagnation alone did not lead to high occurrence of undesirable microorganisms. Findings from this study contribute to our understanding of the effects of stagnation on building water microbiomes and the efficacy of flushing to improve water quality. Under the conditions of this case study, repeated flushing on a weekly timescale during low occupancy periods was not sufficient to maintain chlorine residual and prevent bacterial growth in fixtures. Building managers need to weigh the temporary water quality benefits of flushing against the labor and water resources required considering local context.

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Section: The Building Water Microbiome During Reduced Water Use and F...mentioning

confidence: 99%

Is flushing necessary during building closures? A study of water quality and bacterial communities during extended reductions in building occupancy

et al. 2022

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“…Drinking water microbial communities are constantly adapting to environmental change and are influenced by seasonal fluctuations, water chemistry (i.e., disinfectant residuals), and infrastructure (i.e., pipe materials) ( 26 , 31 – 34 ). From an environmental and public health perspective, insight into the compositional profile of microbial communities inhabiting DWS is of particular importance given their association with processes like nitrification that affect the quality of drinking water ( 27 ) and emerging contaminants (i.e., antibiotic-resistant genes [ARGs]) ( 35 , 36 ) and proliferation of opportunistic pathogens that affect its safety ( 37 – 39 ).…”

Section: Introductionmentioning

confidence: 99%

Evaluating de Novo Assembly and Binning Strategies for Time Series Drinking Water Metagenomes

et al. 2021

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“…The current systematic review greatly expands our previous argument and provides convincing reasons for the appropriateness of Legionella as an indicator of water-based OPs (the major aspect of microbial drinking water quality) in municipal EWSs. However, this review does not imply that Legionella should be used as a sole indicator to infer microbial drinking water quality ( Huang et al, 2021 ). First, Mycobacterium is highly resistant to disinfectant residuals ( Falkinham, 2015 ) and could be more resistant to chloramines than Legionella ( Lin et al, 2011 ).…”

Section: Discussion and Future Workmentioning

confidence: 99%

“…Therefore, in a chloraminated EWS, a low frequency of occurrence and a low concentration of Legionella do not necessarily indicate a low health risk from Mycobacterium . In this case, water utilities might use Mycobacterium and Legionella in combination to better examine microbial drinking water quality ( Lu et al, 2017 ; Huang et al, 2021 ). Future work needs to comprehensively compare the appropriateness of Legionella and Mycobacterium as indicators of water-based OPs and microbial drinking water quality.…”

Section: Discussion and Future Workmentioning

confidence: 99%

Legionella: A Promising Supplementary Indicator of Microbial Drinking Water Quality in Municipal Engineered Water Systems

Chi-qian¹,

2021

Front. Environ. Sci.

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Opportunistic pathogens (OPs) are natural inhabitants and the predominant disease causative biotic agents in municipal engineered water systems (EWSs). In EWSs, OPs occur at high frequencies and concentrations, cause drinking-water-related disease outbreaks, and are a major factor threatening public health. Therefore, the prevalence of OPs in EWSs represents microbial drinking water quality. Closely or routinely monitoring the dynamics of OPs in municipal EWSs is thus critical to ensuring drinking water quality and protecting public health. Monitoring the dynamics of conventional (fecal) indicators (e.g., total coliforms, fecal coliforms, and Escherichia coli) is the customary or even exclusive means of assessing microbial drinking water quality. However, those indicators infer only fecal contamination due to treatment (e.g., disinfection within water utilities) failure and EWS infrastructure issues (e.g., water main breaks and infiltration), whereas OPs are not contaminants in drinking water. In addition, those indicators appear in EWSs at low concentrations (often absent in well-maintained EWSs) and are uncorrelated with OPs. For instance, conventional indicators decay, while OPs regrow with increasing hydraulic residence time. As a result, conventional indicators are poor indicators of OPs (the major aspect of microbial drinking water quality) in EWSs. An additional or supplementary indicator that can well infer the prevalence of OPs in EWSs is highly needed. This systematic review argues that Legionella as a dominant OP-containing genus and natural inhabitant in EWSs is a promising candidate for such a supplementary indicator. Through comprehensively comparing the behavior (i.e., occurrence, growth and regrowth, spatiotemporal variations in concentrations, resistance to disinfectant residuals, and responses to physicochemical water quality parameters) of major OPs (e.g., Legionella especially L. pneumophila, Mycobacterium, and Pseudomonas especially P. aeruginosa), this review proves that Legionella is a promising supplementary indicator for the prevalence of OPs in EWSs while other OPs lack this indication feature. Legionella as a dominant natural inhabitant in EWSs occurs frequently, has a high concentration, and correlates with more microbial and physicochemical water quality parameters than other common OPs. Legionella and OPs in EWSs share multiple key features such as high disinfectant resistance, biofilm formation, proliferation within amoebae, and significant spatiotemporal variations in concentrations. Therefore, the presence and concentration of Legionella well indicate the presence and concentrations of OPs (especially L. pneumophila) and microbial drinking water quality in EWSs. In addition, Legionella concentration indicates the efficacies of disinfectant residuals in EWSs. Furthermore, with the development of modern Legionella quantification methods (especially quantitative polymerase chain reactions), monitoring Legionella in ESWs is becoming easier, more affordable, and less labor-intensive. Those features make Legionella a proper supplementary indicator for microbial drinking water quality (especially the prevalence of OPs) in EWSs. Water authorities may use Legionella and conventional indicators in combination to more comprehensively assess microbial drinking water quality in municipal EWSs. Future work should further explore the indication role of Legionella in EWSs and propose drinking water Legionella concentration limits that indicate serious public health effects and require enhanced treatment (e.g., booster disinfection).

show abstract

Characterizing the premise plumbing microbiome in both water and biofilms of a 50-year-old building

Cited by 18 publications

References 38 publications

Is flushing necessary during building closures? A study of water quality and bacterial communities during extended reductions in building occupancy

Is flushing necessary during building closures? A study of water quality and bacterial communities during extended reductions in building occupancy

Evaluating de Novo Assembly and Binning Strategies for Time Series Drinking Water Metagenomes

Legionella: A Promising Supplementary Indicator of Microbial Drinking Water Quality in Municipal Engineered Water Systems

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