Identification of Factors Affecting Bacterial Abundance and Community Structures in a Full-Scale Chlorinated Drinking Water Distribution System

Vanessa Dias,Emilie Bédard,Audrey-Anne Durand,Philippe Constant,Michèle Prévost

doi:10.3390/w11030627

Vanessa Dias, Emilie Bédard + Show 3 more

Open Access

https://doi.org/10.3390/w11030627

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Abstract

Disentangling factors influencing suspended bacterial community structure across distribution system and building plumbing provides insight into microbial control strategies from source to tap. Water quality parameters (residence time, chlorine, and total cells) and bacterial community structure were investigated across a full-scale chlorinated drinking water distribution system. Sampling was conducted in treated water, in different areas of the distribution system and in hospital building plumbing. Bacterial community was evaluated using 16S rRNA gene sequencing. Bacterial community structure clearly differed between treated, distributed, and premise plumbing water samples. While Proteobacteria (60%), Planctomycetes (20%), and Bacteroidetes (10%) were the most abundant phyla in treated water, Proteobacteria largely dominated distribution system sites (98%) and taps (91%). Distributed and tap water differed in their Proteobacteria profile: Alphaproteobacteria was dominant in distributed water (92% vs. 65% in tap waters), whereas Betaproteobacteria was most abundant in tap water (18% vs. 2% in the distribution system). Finally, clustering of bacterial community profiles was largely explained by differences in chlorine residual concentration, total bacterial count, and water residence time. Residual disinfectant and hydraulic residence time were determinant factors of the community structure in main pipes and building plumbing, rather than treated water bacterial communities.

Highlights

The use of residual disinfectants is a common practice in North America for limiting microbiological contamination in drinking water distribution systems (DWDS) and supplying safe water to consumers
Free chlorine concentration decreased when the water residence time increased from water treatment plants (TW samples) to all sectors of the distribution system (DS samples) and even more so in taps from building plumbing (TAP samples) (Figure 2, r2 = −0.68)
The range of values observed for these parameters reflects the fact that samples within a sector were collected from various types of sampling points such as inlets, dead-ends, as well as points along the sectors encompassing intermediate values

Summary

Introduction

The use of residual disinfectants is a common practice in North America for limiting microbiological contamination in drinking water distribution systems (DWDS) and supplying safe water to consumers. Due to complex interactions between chemical, physical, and operational parameters, bacterial regrowth and proliferation of resistant pathogens in distribution systems can occur even in the presence of a residual disinfectant [1,2,3]. Opportunistic plumbing pathogens (OPPs), such as Legionella and Mycobacterium avium complex, are microbial inhabitants of drinking water systems and the primary cause of waterborne disease outbreaks in developed countries [8,9]. The presence of OPPs in hospital water plumbing is of special concern, leading to waterborne bacterial infections among susceptible patient populations [10,11,12].

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