Microbial Characterization of Drinking Water Systems Receiving Groundwater and Surface Water as the Primary Sources of Water


Earlier descriptions of water distribution systems (WDS) microbial communities have relied on culturing techniques. These techniques are known to be highly selective in nature, but more importantly, they tend to grossly underestimate the microbial diversity of most environments. The goal of this ongoing study is to compare the microbial composition of a WDS receiving different sources of water. To circumvent some of the problems associated with culture-based techniques, sequence analysis of total community 16S rDNA clone libraries was performed. A total of 260 16S rDNA clones were analyzed in this study. Sequence comparisons with existing databases revealed that α-Proteobacteria and Mycobacterium sp. represented nearly 43% and 48% of the total clones examined, respectively. Other bacterial groups identified included members of the genera Legionella, Pseudomonas, and Agrobacterium. Seventy percent of the clones analyzed in this study showed at least 97% sequence identity with sequences available in current databases. While α-Proteobacteria is a numerically dominant group in chlorinated drinking water systems, the abundance of mycobacterial sequences in this study indicates that there are significant differences in microbial community structure between the WDS analyzed. These differences could be attributed to differences in water treatment or receiving water sources between the distribution systems. While some of the genera identified in this study have been associated with some public health risks, it should be noted that analysis of 16S rDNA clones does not confirm the presence of pathogenic strains of any organisms identified in this study, as current methods for detection and identification require several steps including selective enrichment, isolation, and final confirmation via in vitro studies. Future studies will focus on expanding sequencing databases to more accurately characterize these potential differences. This paper was presented at the 8th Annual Water Distribution Systems Analysis Symposium which was held with the generous support of Awwa Research Foundation (AwwaRF).

Meeting Name

8th Annual Water Distribution Systems Analysis Symposium 2006 (2006: Aug. 27-30, Cincinnati, OH)


Civil, Architectural and Environmental Engineering

Keywords and Phrases

Microbial composition; Phylogenetic analysis; rDNA clones; Database systems; Groundwater; Microorganisms; Surface waters; Water distribution systems; Potable water; 16S rDNA clones; Chlorination; Drinking water

Document Type

Article - Conference proceedings

Document Version


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© 2007 American Society of Civil Engineers (ASCE), All rights reserved.