The aim of Theme C proposed for the 11th ICOLD Benchmark Workshop on Numerical Analysis of Dams is to promote a different approach in dam safety assessment, based on reliability methods. In this paper the sliding failure probability of a dam‐reservoir system, under assigned loading conditions, was estimated. Different approaches were applied: the FOSM Taylor and the Hasofer‐Lind methods, besides Monte Carlo simulations. The former are approximated techniques, while the latter are deemed to be exact if the number of samples tends to infinity. For each loading scenario the safety factor was computed as well. The angle of friction and the cohesion along the dam‐foundation interface are both assumed as uncertain parameters and they were used to set up the performance g* functions of the problem, defined on the basis of two different drain conditions. A linear performance g* function was investigated as well, considering the tangent of the angle of friction as random variable. Results in terms of sliding failure probability are quite similar for all methods that assume a Normal distribution for random variables. Concerning Monte Carlo analyses, sampling was generated also from different types of distribution; in these cases a lower probability of failure was attained because they avoid.