The objective of the study was to establish guidelines and priorities for engineering solutions related to the sewer systems and wastewater overflow structures in the City of Montreal. Therefore, modelling of the sewer systems feeding into the sewer mains in the downtown area and the northern section of Montreal was carried out, as was an assessment of the performance of the systems in terms of the risks of sewer back-ups and flooding. Hydraulic and hydrological analyses were carried out using a PCSWMM-based model and calibrated using rain and flow data recorded in real time.