Ontario Construction News staff writer
Mississauga is exploring innovative ways to tackle flooding and water management issues, including the widespread adoption of blue roof technology after facing significant damage from flooding in recent months.
Flooding can cause extensive damage to homes, businesses, and infrastructure, while disrupting essential services such as transit and electricity and, in the long term, flooding can also harm ecosystems and pollute local water sources, including Lake Ontario. To address these challenges, cities like Mississauga are turning to sustainable solutions, such as blue roofs, to help manage stormwater.
This year, Mississauga became the first city in Canada to implement a CSA-compliant “smart” blue roof system, in partnership with Credit Valley Conservation (CVC). The system, located at CVC’s administration building (1255 Old Derry Rd.), is designed to capture and store up to 60,000 litres of rainwater, providing flood protection and water conservation benefits.
The project won a 2025 Clean50 Top Project Award, showing its potential to inspire similar initiatives across Peel Region and Canada, as many municipalities are facing increased rainfall due to climate change.
Traditional roofs are designed to shed water quickly, directing it through downspouts and into the municipal stormwater system. In contrast, blue roofs are engineered to capture and store rainwater. By holding rainwater temporarily, blue roofs reduce the volume of water entering the stormwater system during heavy rainfall, helping to prevent flooding and easing pressure on city infrastructure.
Some of the collected rainwater evaporates, cooling the building and reducing the need for air conditioning. The rest can be diverted for non-potable uses, such as irrigation or toilet flushing, which reduces water consumption and lowers utility bills.
A “smart” blue roof uses advanced technology, including sensors and programmable logic controls, to manage captured rainwater efficiently. The system decides, based on pre-set parameters, whether to store the water for cooling, release it into the stormwater system, or redirect it to a storage tank for future use. This adaptive stormwater management technology helps reduce the risk of downstream flooding and minimizes the strain on Mississauga’s stormwater infrastructure.
CVC’s smart blue roof has already shown impressive results. Preliminary findings include:
- successfully captured and stored rainwater from all storms between May and October 2024, including heavy rainfall in July and August.
- 51 per cent of the captured rainwater evaporated, providing cooling benefits for the building.
- 42 per cent of the rainwater was harvested and treated for use in toilet flushing.
- Only seven per cent of the water was released into the municipal stormwater system during dry weather.
These results led to a 75 per cent reduction in purchased potable water used for toilet flushing at the CVC building. The success of the project earned it a 2025 Clean50 Top Project Award, underscoring its potential to inspire similar initiatives across Peel Region and Canada.
The CVC’s smart blue roof is being used as a “living lab” and a model for future projects aimed at addressing climate change and urban flooding. Mississauga’s Green Development Standard (GDS) encourages sustainable development, and the city continues to explore low-impact development strategies to meet the challenges posed by climate change.
Smart blue roofs use sensors and control systems to monitor and manage rainwater levels. The system adjusts water storage based on weather forecasts, ensuring that the roof can accommodate heavy rainfall. If the system exceeds its storage capacity, water is released safely through overflow routes. This technology helps ensure that the building and surrounding infrastructure are protected from flooding, while also optimizing the use of captured rainwater for building cooling, irrigation, and non-potable purposes.
Blue roofs offer an opportunity for businesses and homeowners to manage stormwater, reduce water costs, and mitigate the impacts of climate change. Installing a blue roof requires a feasibility study to evaluate the building’s structural capacity and determine the most effective design for water storage and use. The project’s success in Mississauga sets the stage for similar initiatives across Canada, where municipalities are increasingly facing the challenges of climate change.
As the first city in Canada to implement a CSA-compliant smart blue roof, Mississauga is demonstrating leadership in the field of sustainable urban development and stormwater management.
As weather patterns continue to change, wide-spread community adoption of technology like blue roofs can help to mitigate the impacts of heavy rainfall and storms. Learn more about CVC’s and the City of Mississauga’s smart blue roof project.