The tap water quality safety in cities matters greatly for national economy and people's livelihood. This paper, based on the high organic matter and high ammonia nitrogen water supply and drainage system, explores what is the impact law of different water treatment processes on the water supply and drainage system, and suggests that the ambient temperature has a greater impact on the water temperature; what is the change laws of turbidity, ammonia nitrogen and oxygen consumption in the water supply and drainage system in different seasons and finds that there are seasonal differences significant in color and turbidity. The biological pretreatment process has little impact on the two. The ammonia nitrogen content in water source is slightly higher in summer than in winter. The pretreatment process can effectively reduce the ammonia nitrogen content in water; but the oxygen consumption drops a little after biological pretreatment. We make OUT statistical analysis and DNA matching in order to clarify the radial distribution in the space and diversity composition of the microbial community in the tap water supply pipeline. The results reveal that in large- diameter pipeline microorganisms disperse more on the top and bottom than in the middle. There are predominant bacteria on the top and bottom part but most diverse bacteria in the middle part. These fruits can provide the basis for improving the water supply and drainage treatment and water quality.
