Stormwater drainage from waterproofed surfaces

All the techniques and facilities for controlling stormwater flow and water runoff by retention or infiltration or for taking care of the collection, possible storage and, if necessary, the stormwater and runoff-water treatment when the pollution they bring to the aquatic environment may seriously impair the effectiveness of sanitation systems. Indeed, rainwater by running off on waterproofed surfaces (roofs, roads, storage areas, etc), may carry pollutants (organic matters, heavy metals, hydrocarbons, etc).