Étude de l'évolution de la qualité de l'EAU de ruissellement de toiture au cours des événements pluviaux

In the rainwater harvesting system, the first contaminated volume of runoff from a rooftop after a rainfall is assumed to contain most of the pollutants. Researches have shown that removing the first part of water may improve the quality of stored water. It is necessary to study the initial rainfall quality and the quality changes at the beginning of the rainfall event In this study, a special harvesting system was setup in two houses located in two different areas in the Île-de-France and 30 storm events for 2 years were collected. The quality of the rainwater was analysed through the following parameters: pH, conductivity, TSS, turbidity, DOC, enterococci, Escherichia coli, total flora at 22°C and 36°C. The results show that the difference in the quality of the roof runoff water between the two sites is important because of the various factors (the intrinsic characteristics of the roof, the environment of the collection, the meteorological factors...). For the turbidity and the conductivity, some of the collection events show decreasing trends which means that the improvement of the roof water quality during the rain can be observed. On the other hand, the changes of all the microbiological parameters are heterogeneous and this testifies to the fact that this improvement is not systematic.