Stormwater management is a key factor of sustainable urban systems. The quantitative objective of reducing impacts on sewage systems has emerged since the 1960s. More recently, the mastery of micro-pollutants contained in stormwater runoff has emerged as a new priority, imposed by regulation (including the Water Framework Directive) to less impact on the receiving waters. Nonetheless many technical and organizational uncertainties are associated with the improvement of the quality of water discharged to aquatic environments through the implementation of “innovative” management practices for the control of micropollutants. So how can we talk about innovation? How is it produced and can it be transferred? The notion of “design” differs from the positivist idea of innovation as “plan”; rather, it is conceived as a process of adaptation /repair in relation to already existing infrastructures and social practices. This work is based on four different management devices to treat road runoff in the Paris region. We first show that innovation does not emerge ex nihilo but rather as a form of adjustment / re-design of pre-existing infrastructures and skills. Second, the establishment of such devices is not a “linear” process but a back-and-forth movement between the idea, its empirical characterization and its experimentation. In the end, we give account of the “transitional” nature of the technical device that changes in the process depending on the actors and skills developed through fieldwork.