Stormwater is a real problem quantitatively with the floods, but also in qualitative terms as demonstrated by numerous studies since the 90s on the importance of pollution discharges of urban wet weather and impact on the natural environment. They have also led to the finding of increased stormwater pollution in the case of CSOs over separate networks.

Our knowledge has evolved and led to the implementation of a variety of solutions which may have learned from initial feedback in both urban and suburban on infrastructure.