This research undertaken at the University of Sheffield aims to provide a better understanding of the interaction above/below ground urban floods. A newly constructed unique experimental facility has been developed in the water lab, and it includes a sewer system, composed by 3 main pipes, 6 manholes and a CSO (Combined Sewer Overflow), and a preliminary urban surface with the slope 1/1000. This paper describes the experimental facility that has been built, how the system is managed in real time control using Labview software, which methodology will be applied to increase the understanding of the exchange flow-rate between an urban surface and a below sewer system and it presents preliminary results obtained comparing physical results with computer software results such as InfoWorks, SWMM and SIPSON (NUNO MELO et al., 2012). Finally, the PIV system (Particle Image Velocimetry) that will be used for the acquisition of the images during the event of flooding is briefly explained. This last step will be useful for the comparison between 3D digital maps created by standard software against real physical results.