Landscape and Horticultural Irrigation Using Roof-Derived Stormwater

Plant growth experiments on tomato plants and rye grass were carried out over 5 months using water derived from the overflow from an
established experimental blue green roof. This blue green roof stores water just below the growing medium and transmits it up to the
growing plants by capillarity. This allows the planting of non-drought resistant vegetation, in contrast to the sedum’s that are the usual
choice for green roofs (Cirkel et al 2018). At times of storm there is often an excess and such roofs are often used in stormwater source
control applications under real time control in response to rainfall radar information (Voeten et al 2016). Currently the water ejected from
them, in advance of a coming storm, is often simply released to sewer or surface watercourses, in the latter case with potential to release
pollutants such as inorganic nutrients. An attractive alternative is to store this water for use in urban irrigation or, where nutrients are
available, fertigation. The blue-green roof derived water showed a growth benefit presumedly derived from the release of nutrients from
the growing medium on the blue-green roof, compared to the tap water control