Effect of grey water reuse on hydraulic performance of water supply pipes networks

ABSTRACT Water shortage and performance decline of the water supply pipe network have increased the challenges of accessing satisfactory water services. Reusing grey is considered a solution to this situation. In the present study, the effect of using grey water on the hydraulic performance of the water supply pipe network is investigated. Three scenarios for greywater recycling are studied: the no greywater reuse scenario, the satellite scenario, and the on-site scenario for two water feeding systems, i.e., with and without roof tanks. Hydraulic analysis of these scenarios is carried out by simulating a case study pipe network using the WaterGEMS software. On-site and satellite greywater reuse systems significantly increased the pressure head by 18 and 20%, respectively, at peak consumption. Reusing treated grey water also significantly reduced velocity values in the network, with velocities less than 0.5 m/s in some pipes even at peak consumption, making these pipes vulnerable to sedimentation. Furthermore, the performance was simulated under a break in crucial pipes, showing that greywater reuse significantly enhanced the network's reliability. The study also examined different ratios of water consumption reduction and treated greywater reuse through fourteen scenarios, indicating that reusing greywater along with a water consumption reduction plan reduced water needs by 42.8%.