Catastrophic events in recent years have shown that complex interdependencies between critical infrastructure systems can result in additional vulnerabilities, such as cascading failure, prolonged downtimes and network congestion. This paper proposes a novel method for modelling these interdependency effects in order to inform more effective strategies for improving disaster resilience. The method combines a Markov chain model for failure and recovery processes affecting operability at the asset-level, with a minimum cost flow model for the joint simulation of flows in interdependent networks. As a proof-of-concept, the model is applied to analyse the resilience against flooding of two of London’s most important infrastructure systems: the metro network and the electricity distribution grid.