We propose a cross-domain methodology to model and evaluate efficiency indicators of a Medium Voltage/Low Voltage (MV/LV) smart grid and its SCADA, interdependent, at physical layer and ICT layer, with water and gas urban networks. Models account the interdependency among the networks, a) adding, when possible, to the main sources of each network, sources belonging to the other networks; b) looking at the active components of water and gas networks energized by the electrical grid and c) considering ICT, which represents a common means, supporting and interconnecting SCADA devices of all the networks. Models use domain simulators to faithfully represent each physical network, and transversal simulators, to represent together the three interdependent physical networks and their SCADA systems. Models built by domain simulators are used to validate models built by transversal simulators. Efficiency indicators, and particularly, the Quality of Service of each network, are predicted along planning and operation scenarios. © 2014 DIME UNIVERSITÀ DI GENOVA.