Toward better practices in infiltration regulations for urban stormwater management

Infiltration of runoff at the plot-scale is increasingly considered as an effective tool to improve urban water management. As a consequence, authorities in different countries adopt regulations prescribing the infiltration of stormwater in new developments. Here we apply a simple sizing procedure for plotscale infiltration facilities to examine the consequences, in terms of implementation, of typical regulation standards. Considering the relevance of different parameters in the sizing of infiltration facilities, local hydraulic conductivity emerges as the most relevant factor. Because of the importance of local infiltration capacity, current regulation standards based on a single constraint applied everywhere can require from developers highly different compliance efforts and can prove ineffective for stormwater management. We argue that regulations fixing constraints according to plot-scale soil characteristics are feasible and more effective.