- Communities depend on increasingly complex critical infrastructures to meet residents' daily needs and to facilitate emergency response. The potential for cascading failures could intensify the consequences of disasters and complicate the process of planning for effective emergency response. This article presents a methodology for conducting a vulnerability analysis based on simulation of water distribution's role in emergency response under various complex-disaster scenarios in which incapacity of the water system is coupled with an urban fire. The analysis reported here was run on a virtual (but detailed and realistic) small-town water distribution system to permit candid discussion of the insights derived from the vulnerability analysis and to avoid disclosing the vulnerabilities of a real system. The analysis methodology presented may be adapted to fit the needs of real communities. The results of these simulations are used to demonstrate a procedure for designing and testing mitigation methods to improve the community's robustness and resiliency. Most of the mitigation techniques involve infrastructure upgrades, and a cost-benefit analysis of these approaches is included as an aid to decision making. Discussion of how utility managers and emergency planners may adapt the analysis technique to their own systems is included throughout.2013 American Society of Civil Engineers.