In this study, the definition and standards of the block system, and the block isolation confirmation method were reviewed to establish an effective block system. The study target area was selected and a block system construction plan was established. First, for small blocks that cannot find unused pipelines connecting between small blocks, a method of operating small blocks by partially changing the small block boundaries planned in the drawing to match the site conditions can also be an effective method for block system management. The second is to secure water quality stability through flushing. Blocking the flow and changing the flow direction by operating the valve to confirm the small block isolation is causing red water and pollutants. First of all, it is necessary to examine the method of discharging the accumulated pollutants and red water in the pipe. Finally, Before the block isolation confirmation, the boundaries were not divided by drainage or unit area, and the drainage amount could not be analyzed because flow measurement facilities by small block were not equipped. However, after the block isolation was completed, it was possible to calculate the flow rate according to each small block by installing a flow meter at the inlet point. As a result of measuring the flow rate for each small block according to the block isolation confirmation, the SJ-3 small block had the highest average flow rate with 88.9 %, and the SJ-2 small block had the lowest average flow rate with 66.2 %. In addition, it is necessary to subdivide the water supply area for small blocks with low flow rate. It is judged that effective pipe network management will be possible if a small flow rate monitoring system is installed at the inlet point of the subdivided water supply area.