The soil and planting in a green roof will capture and temporarily hold 90% of the stormwater from a typical rain event, and between 30%-60% annually [2]
Rainwater can be collected for both potable and non-potable use from Green Roofs after disinfection and filtration
The average water retention for a roof without a Green Roof is only 24% while one with a Green Roof is 80% [3]
Green Roofs allow water management plans to use smaller stormwater retention basins, and the water that does runoff will be naturally filleted due to the plants absorbing some of the pollutants in their root biomass