The invention relates to modular elements for building a storage basin, to a network obtained by assembling a plurality of modular elements, to a supporting structure, to a storage basin and to a process for obtaining a storage basin. The modular element according to the invention is provided in the interior with a network element constituted by main half joints (10), secondary half joints (11) and tertiary half joints (10), vertical channels (8,15), oblique channels (9), compartments (18), and is provided with joint elements (16,17). The network comprises horizontal annular channels and main, secondary and tertiary joints connected by vertical and oblique channels. The storage basin comprises a supporting structure at the interior of an insulating structure obtained by assembling the modular elements. The process for obtaining a storage basin comprises the assemblage of the modular elements and casting the hardening material in the network obtained by assembling the modular elements, forming the supporting structure.