With the growing adoption of renewable energy resources in power grid, co-optimizing operation water and distribution networks (WDNs PDNs) increases flexibility both systems. The optimal flow problem (OWPF) is formulated to manage resource utilization across WDNs multi-phase PDNs. nonlinear WDN hydraulic constraints PDN ac equations render OWPF nonconvex. This paper formulates a convex (C-OWPF)...