A methodology to prioritize the water supply system (WSS) upgraded by water safety plan (WSP) is described. It is based on the risk management and water quality testing to assess safe water supply strategy. The main aim of this study tries to effectively improve the phenomenon of water safety in Taiwan. Pingding, the south-western WSS in Taiwan, was chosen as the case study because the granule of aluminum of source water in this area were easily beyond the regulation threshold. Besides, this district was frequently hit by high turbidity events during raining seasons that always result in overloading for water treatment processes and then occasionally run customer to doubt or complaint the tap water quality. Compared with the traditional way of World Health Organization (WHO), the methods in this research attempted to simplify the complication of risk matrix by deriving big data from "Customer Service System (CSS)" and "Alarm Data Transfer System (ADTS)". The methodology developed in this research not only provides the systematic model to follow but also reduces the cost of labor and time effectively. In fact, it has made a valuable contribution to the practical tasks. The original Total Risk Score (TRS) was reduced from 47 to 33 by conducting Taiwan Water Corporation (TWC) WSP. The WSP ten-step guideline shows that the WSP has achieved considerable results. It is worthwhile to follow the case study as the main body and promote it to the whole company in TWC. © 2020, Chinese Institute of Civil and Hydraulic Engineering. All right reserved.
