Infrastructures are becoming increasingly interconnected and it is essential to develop models that account for interdependencies between infrastructure systems at different scales. This paper presents a network model designed to achieve this, aimed at a local scale. Infrastructure systems are considered as a network. Vertices, which represent processes of production, consumption, transhipment and storage of resources (commodities), are connected by edges that capture commodity flows. Optimal performance of the network under normal and extreme conditions may be found by minimising the cost of commodity flow. The model is described, and the performance of interdependent infrastructure systems (energy, water and wastewater) during floods is demonstrated, using Monte Carlo simulation. The advantages and limitations of the model are considered before future developments are outlined.