From Source to Tap: Tracking Microbial Diversity in a Riverbank Filtration-Based Drinking Water Supply System under Changing Hydrological Regimes

In drinking water supply, riverbank filtration (RBF) is an efficient and cost-effective way of eliminating pathogens micropollutants using a combination biotic abiotic processes. Microbial communities in the hyporheic zone both contribute to are shaped by these quality at point consumption turn influenced source microbiome, treatment distribution system. Understanding microbial community shifts from tap factors behind them instrumental maintaining safe delivery. To this end, RBF-based supply system were investigated metabarcoding one-year sampling campaign. Samples collected river, RBF wells, treated water, consumer’s tap. Metabarcoding data analysed context physicochemical hydrological parameters. diversity as well cell count decreased consistently surface While Proteobacteria dominant throughout system, typical river microbiome phyla Bacteroidota, Actinobacteria, Verrucomicrobiota replaced Nitrospira, Patescibacteria, Chloroflexi, Acidobacteriota, Methylomicrobilota, archaeal phylum Nanoarcheota water. Well differentiated chemistry, wells with high concentration groundwater derived iron, manganese, sulphate, taxa related iron sulphur biogeochemical cycle predominant, while methane oxidisers characterised more oxic wells. Chlorine-resistant filtration-associated (Acidobacteria, Firmicutes, Bdellovibrionota) emerged after treatment, no potentially pathogenic identified consumption. River discharge had distinct impact on indicative vulnerability climate change. Low flow conditions anaerobic heterotrophic (Woesarchaeales, Aenigmarchaeales, uncultured bacterial MBNT15 WOR-1), implying reduced efficiency degradation organic substances. High was associated emergence taxa. Better understanding systems contributes preserving safety future changing environment.