Reducing discharge flow does not aim to decrease the total volume of stormwater, but rather to slow its release into sewer networks through temporary detention. This approach helps mitigate the negative effects of intense rainfall events — often referred to as “rain peaks” — by preventing sewer overloads and the saturation of wastewater treatment plants.
The main challenge for many municipalities is managing these peak flows: heavy rainfall can exceed the capacity of drainage infrastructure, causing flooding and combined sewer overflows. Blue roofs offer a simple and effective solution to this problem. A blue roof retains rainwater on the rooftop and then releases it gradually — typically within 24 hours after the event — into the sewer system or a stormwater management system.
This method significantly reduces pressure on municipal infrastructure and lowers the risk of flooding. It also offers clear advantages: installations are often less costly and more discreet than traditional retention basins, while being fully integrated into the building envelope.