The City’s first step was to conduct several studies to identify the affected areas and determine which buildings were contributing to the problem. It found that 373 of the 623 homes with pitched roofs were illegally discharging their eavestrough water into the combined sewer system through the foundation drain, thereby overloading the system and violating municipal by-laws. The City had regulations in place prohibiting such designs, but these hookups persisted.
Faced with the prospect of an increasing number of basement flooding incidents, Quebec City implemented a downspout disconnection program that achieved a 100% compliance rate due in large part to an awareness campaign targeting affected homeowners. The affected neighbourhood, Maizerets, is located in the Limoilou district and is over a century old. It is served by a combined sewer system that has often resulted in basement flooding during rainfall events, as many buildings upstream had their downspouts connected directly to the municipal sewer system. The area is also served by a tidal barrier designed to prevent the St. Lawrence from backing up in the municipal sewer system, but this also increases the risk of sewer backup during rain events because the system cannot drain easily.