In the Republic of Korea, multi-regional water supply pipelines were intensively laid during the rapid economic growth period; however, these pipelines are now aging. The cost of renewal of the aged pipelines would be enormous. Therefore, limited resources need to be distributed effectively in accordance with the priority of renewal. In this study, the risks involved in the multi-regional water supply pipeline of region K were calculated and assessed for setting the priority of renewal. The probability of failure of the pipeline was calculated through a quantification theory, and the effects of failure on the water supply pipeline were calculated by interpreting a pressure driven analysis. The risk considering the probability and consequence of failure comprehensively was found to be the largest at section A12. Three alternatives were considered for risk reduction, and the effect of each alternative on the risk reduction was analyzed. As a result, the construction of double piping by laying a new pipeline was found to be the most effective measure for risk reduction. The results of this study can be utilized as the basic data for establishing an investment plan for the renewal of the water supply pipeline and asset management plan.