Reproducible Microbial Community Dynamics Of Two Drinking Water Systems Treating Similar Source Waters

Understanding whether the spatiotemporal dynamics of the drinking water microbiome are reproducible in full-scale drinking water systems is an important step in devising engineering strategies for effectively managing and manipulating it. However, direct comparisons across full-scale drinking water systems are challenging because multiple factors, from source water to treatment process choice and configuration, can be unique to each system. This study compared the spatiotemporal dynamics of the drinking water microbiome in two drinking water treatment plants (DWTPs) with identical sequences of treatment strategies. These DWTPs treat source waters from the same river system and treated drinking water is distributed within the same large-scale distribution system (DWDS) with similar disinfectant residual regiments. Dissimilarities in source water communities were tempered by the predisinfection treatments, resulting in highly similar postfiltration microbial communities between the two systems. However, high community turnover due to disinfection resulted in highly dissimilar microbial communities in the finished water between the two systems. Interestingly, however, the degree of similarity of the microbial communities in the two systems increased during transit through the DWDS despite the presence of a disinfectant residual. Overall, our study finds that the drinking water microbiome demonstrated reproducible spatial and temporal dynamics within both, independent but nearly identical, DWTPs and their corresponding DWDSs.