Bacterial communities in a neotropical full-scale drinking water system including intermittent piped water supply, from sources to taps

Abstract

Understanding the microbial ecology of drinking water systems is crucial to delivering safe water. Intermittent water supply is a substandard water service that is common around the world; however, we do not yet understand how this service influences the communities of microorganisms in distribution systems. We used rRNA gene metabarcoding alongside traditional measurements of water quality to assess bacterial diversity and structure in a neotropical drinking water system with continuous and intermittent supply. We sampled from source and treated water before distribution at three drinking water treatment plants, household taps across the distribution network, and in an intermittent supply zone immediately after supply restarted and 24 hours after. Each treatment plant had a diverse microbiome, dominated by Proteobacteria; treatment and distribution changed the diversity and composition of bacterial communities. Communities differed at the start of IWS supply and 24 hours after, and several taxa were only found in first flush samples, suggesting intrusion of new bacteria into pipes or regrowth of bacteria between supply cycles. Pseudomonas was found to be more common in IWS samples than elsewhere in the network. Unique taxa found only at the restart of IWS service have the potential to be used as indicators of intrusion in future research.