Assessing the role of the drinking water distribution system on the bacterial community in public buildings

Abstract: Safe drinking water is important and the water quality is related to the microbial community. In this study, two public buildings that receive drinking water at different locations in a distribution system were selected as sampling points. The drinking water samples in the buildings were sampled every week to investigate the impact of the distribution system on the microbial community. The sampling was carried out for two months, except a week of public holidays in the middle of it, which allowed us to assess the impact of water stagnation on the bacteria in the water. The research methodology is to analyze the cells through flow cytometry, and preserve the DNA in the water through filtration for further research. The traditional tests for microbes, chemicals and metal analyses in the standard water quality tests were also submitted to Eurofins for testing. It is found that the drinking water distribution system has a significant impact on the microbial community, and it was detected that more intact cells in building further from the DWTP was 240% higher than the one closer to the DWTP on average. The stagnation of water led to an increase in the number of total cells and percentage of the high nucleic acid (HNA) bacteria content in the water. In particular, the TCC was 120% and 220% higher after stagnation in school 1 and school 2, respectively. In addition, higher the temperature results in a higher cell content in the distribution samples. The distribution samples had lower cell count and fewer bacterial types compared to other samples.