Storm tanks are an increasingly solution used to control floods caused by the increase of runoff flows generated by rain. To expedite the construction of these infrastructures and reduce downtime of urban supplies plastic modular elements as basic building structures are used. This paper presents the characterization of this sort of modular elements determining its energy dissipation to the passage of the water and comparing the hydraulic behavior of modular deposits to conventional ones. This paper justifies the use of computational fluid dynamic techniques (CFD) for characterizing hydraulic behavior of these modular elements based on three-dimensional models. These models have been validated by an experimental prototype built in laboratory. This one consists of a channel along which various completely monitored modular blocks are disposed in order to analyze both, circulating flows and water levels reached at different points of the system. The final result is a validated and calibrated model that allows to represent the behavior of this kind of infrastructures against strong intensity storms. A one-dimensional model of such structures is proposed as a way to join it with a specific computational model of drainage networks analysis as is the case of SWMM. Finally, a comparison between the results obtained by CFD techniques and those obtained after adjustment in SWMM is shown.