The impact of flushing the drinking water distribution system pipeline on the quality of drinking water and microorganisms

As an important measure to maintain water quality, pipeline flushing, while capable of removing deposits within the pipeline during the process, can also have short-term effects on drinking water quality and microbial communities. This study aims to investigate the impact of pipeline flushing on water quality and microbial communities in drinking water distribution systems (DWDS). By selecting sampling points in the DWDS of a city in northeastern China, water samples were collected before and after flushing, and subjected to physical, chemical, and microbiological analyses. The results showed that pipeline flushing significantly altered water quality parameters, with turbidity failing to meet the drinking water standard after flushing. Specifically, turbidity increased from an average of 1.6 NTU to 2.5 NTU after flushing, but recovered to below pre-flushing levels after two weeks. Residual chlorine content was below the standard before flushing but reached or exceeded the standard of 0.05 mg/L at most sampling points two weeks after flushing. Microbial community analysis revealed a significant increase in bacterial diversity after flushing, with Proteobacteria becoming the dominant phylum, replacing Actinobacteriota before flushing. Additionally, compositional analysis showed that pipeline flushing deposits were primarily composed of Fe₃O₄、SiO₂、CaCO₃, confirming the removal of pipe scales during the flushing process. This study quantified the specific impacts of pipeline flushing on water quality and microbial communities, providing a scientific basis for optimizing DWDS management strategies.