Changes of microbial communities in loose sediments with accumulation time in chlorinated drinking water distribution systems

'Yellow water' issues frequently occur in drinking water supply systems on university campuses, primarily caused by the resuspension of loose sediments within pipelines, which may pose high potential microbiological risks. In order to investigate the accumulation of sediments accompanying microbiological risks in municipal pipelines, 'water + sediment' samples were collected periodically over two semesters in a university campus exhibiting divergent temperature patterns. Results indicated that sediment quantity increased rapidly within a short period; however, microbial biomass did not increase significantly. During the second semester with rising temperatures, the abundance of potential pathogens like <i>Legionella</i> spp. and <i>Mycobacterium</i> spp. increased markedly. Microbial community structure underwent an obvious succession over time in both semesters. This study found that short-term sediment accumulation in university campus drinking water supply systems did not pose immediate microbiological risks under the studied conditions. Pipeline pre-flushing before the start of each semester was recommended to mitigate microbiological risks.