Stormwater Change in Existing Urban Areas

In the Netherlands, most new built urban areas have sustainable water systems where stormwater is separated from wastewater and utilised in the urban environment. For existing areas it is more difficult. There are good examples where (1) an intensive public participation process has been set up, (2) other problems in the living area have been tackled, (3) a vision has been set up in one day and (4) uncertainties have been coped with in a process of learning by doing. Still, most of the projects are too expensive. A significant social innovation is needed to come up with plans that are acceptable both socially and financially. Based on the experiences, the KWW Strategy has been set up, in which a learning process is organised around the uncertainties that stormwater projects in the existing urban environment reveal and Tacit Knowledge is put into play. The Water Coalition shows that it might be possible to lower the costs significantly, but people involved have to learn to play a new role. This change – social innovation – needs time.