Impact of temperature and water source on drinking water microbiome during distribution in a pilot-scale study

This study utilized a pilot-scale distribution network to examine the impact of temperature increases (16 °C, 20 °C, 24 °C) and source variations (treated ground- and surface water) on bulk and biofilm communities over 137 days. Microbial characterization employed flow cytometry and 16S rRNA gene-based amplicon sequencing to elucidate bulk-biofilm interactions. Bacterial bulk cell densities increased with higher temperatures, while water source variations significantly influenced bulk cell densities as well as the community composition. Additionally, growth curves were fitted on the flow cytometry results, and growth rates and carrying capacities were higher with treated groundwater at elevated temperatures. Conversely, biofilm cell densities remained unaffected by temperature. A mature biofilm was observed from day 70 onwards and a core biofilm microbiome, resilient to temperature and water source changes, was identified. These findings emphasize the importance of water source quality for maintaining biological stability in drinking water systems, particularly in the face of changing environmental conditions.