A description of the Tous Dam break as a case study for flood model development and validation purposes is presented. The corresponding data set was put together during a joint European project named Investigation of extreMe flood Processes And unCerTainty (IMPACT) with the aim of testing numerical models of flood propagation, including the treatment of urban areas. The case study is based upon the failure of Tous Dam in Spain and the flooding of Sumacárcel, a small town located 5 km downstream. Tous Dam broke due to overtopping on October 20, 1982. This event exemplifies the failure of a major flood control structure with considerable risk for population and damage to properties. The paper describes Tous Dam, the event that led to its breaching, the effects of the flood downstream and the inundation of the town of Sumacárcel. The information provided together with the referenced data set allows for mathematical modelling of the breaching and flooding processes, including the town, and can be used for validation of mathematical models against real-life data.