SRP341337 PRJNA771194 The Impact of Pipe Material on the Diversity of Microbial Communities in Drinking Water Distribution Systems Pipe material can impact the development of biofilm in drinking water distribution systems (DWDS) that can harbor pathogens and impact drinking water quality. Annular reactors (ARs) with cast iron and cement coupons fed with chloraminated water from a municipal DWDS were used to investigate the impact of pipe material on biofilm development and composition. Biofilm communities on coupons were characterized using 16s rRNA sequencing. Sequencing data were analyzed to examine the impact of pipe material on the diversity, bacterial composition, and opportunistic pathogen prevalence in pipe biofilm.