The current design practice of sewer systems is not sufficient to capture the effects of the chemical processes induced by the aggressive nature of wastewater on the mechanical response, leading to the premature failure of the concrete sewer pipes. In this project, an advanced numerical model for the coupled chemo-mechanical response of concrete sewer systems subjected to chemical degradation is being developed. This will enable to model the occurring chemical reaction, the formation of reaction products and their effect on the degradation of mechanical properties of the pipes. The model will be verified and calibrated extensively by large-scale loading tests and by measuring the chemo-mechanical deterioration of old sewer pipes, accounting for the effects of several environmental conditions. The obtained results of the approach will be translated into guidelines for the condition assessment of existing infrastructure and durability design rules towards a performance-based design approach.