In plumbing water systems (PWSs), there are two main layouts for water pipe networks (WPNs) within buildings: branched and looped layouts. The aim of this study is to introduce an approach for improving the performance of PWSs using looped water pipe networks within buildings. This approach is applied to a case study of branched configuration that is firstly changed to a looped configuration with the same pipe diameters, secondly to a looped configuration with the same discharge and velocity, and thirdly to the same branched configuration with double the pipe diameters. All cases were analyzed for cost and hydraulic reliability in terms of resilience index, minimum surplus head, failure index and demand node's flow path. EPANET software was used for hydraulic analysis of all cases. It is concluded from this study that replacing branched configuration of PWSs by looped configuration improves the hydraulic reliability and minimizes the costs of the PWSs.