24 artificial neural network blending complex network theory disinfection by-products district metered areas dual response surface optimization (DRSO) energy recovery systems graph partitioning intermittent water supply leakage mathematical model modularity multiple regression analysis multiple source waters blending optimization (MSWBO) non-revenue water optimization pressure pressure-driven pump real time control release of heavy metals (HMR) runaway conditions snapshot simulation topological analysis unsteady flow valve vulnerability water distribution modelling water distribution network