Is it possible to combine rainwater use with green roofs?
Most definitely, and it is a great way to save on additional costs. With up to 50-90% of precipitation being retained by the green roof build-up any excess water can be collected and stored in a modern rain management system or cistern. Another benefit is the vegetation and substrate layer acting as a water filter; these layers hold back particles, dust, solute pollutants, and even heavy metals. The excess rainwater can then be used to irrigate the roof, used as toilet water, or any other available purposes. Water coming from the roof can have a light brown tint as a result of the humic particles in the substrate layer; therefore, it is not suitable to be used as wash water. If run-off water is used for toilets it is best to have a sign indicating ‘natural cloudiness’ in order to avoid confusion. Calculating storage capcacity: It should be noted that during the summer months most rainwater is used by the green roof itself and this should be incorporated into the calculation for the cis
