Extracellular DNA in Monochloraminated Drinking Water and its Influence on DNA-based Profiling of Microbial Community

In this study, we report for the first time that the total DNA extracted from monochloroaminated drinking water contains a high fraction of eDNA. Drinking water samples were obtained from Locations 1 (~20-year-old pipeline) and 2 (~7-year-old pipeline). At Location 1, 40-120 ng of eDNA was found per litre of sampled water, which accounted for 52 ±12 % of total DNA, while at Location 2, 5-8 ng of eDNA was found per litre of sampled water, accounting for 42±8% of the total DNA. We further showed that the removal of eDNA reduced α-diversity, increased community evenness, and changed relative abundance of detected taxa. Our findings lead to future research questions about the source, fate and implications eDNA in DWDS.