Ageing infrastructure increasingly poses a major challenge. Since many infrastructure assets show some degree of deterioration and approach the end of their originally intended design life time, questions arise whether these assets can safely remain in operation. Port infrastructure is no exception. Existing quay walls need to be assessed as part of lifetime extension programs in order to guarantee safe handling of ships and to verify whether terminal- and ship loads are still acceptable, considering the degradation these structures have experienced (e.g. corrosion). At the same time, original design verifications do not comply to the requirements of modern design codes, and so far, there is limited guidance for the assessment of existing quay walls (and civil structures in general). In order to make risk-informed decisions on the remaining service life a reliability-based assessment is a convenient option to combine the data of existing structures, including degradation, with the intended service load conditions. The complexity of quay walls usually results in the need to model its structural behaviour, including soil-structure interaction using the finite element method (FEM). In particular at low failure probabilities, an FEM-based analysis often results in noisy and incomplete output, which poses a challenge for existing reliability methods. This paper demonstrates how FEM-based reliability analysis of quay walls can be carried out in a robust manner using adaptive meta-modelling using Gaussian process regression. The approach enables reliability calculations for low probabilities of failure (i.e. in the order of Eurocode requirements), with a moderate number of dimensions (i.e. 10 to 20), by evaluating the limit state function about hundreds of times only. This implies that calculations can be performed within several hours, which makes the analyses feasible for real-life engineering applications by practitioners. Furthermore, the presented case study highlights the main influencing sources of uncertainty in quay-wall engineering.