A container structure (100) for fluids, of plastic material, comprises a side wall (10), a bottom wall (20) and a head wall (30), which defining a closed innner chamber (40) having an inner side wall (10a). In addition, the container (100) comprises at least one inlet/outlet mouth (31), for the movement of the liquid towards/away from the inner chamber (40) and differential pressure means for making a pressure (50, 70) in the inner chamber (40) with respect to the outside of the container. In particular, the mouth (31) allows, furthermore, te operations of loading/unloading the fluid into/away from said container. In particular, the inner chamber (40) comprises a plurality of stiffening ribs (41) obtained by variation of the thickness of side wall 10 and extend for a predetermined thickness with respect to the inner side wall (10a) del container. The stiffening ribs (41) are adapted to opposing the container to collapse when the differential pressure means for making a pressure (50, 70) make in the chamber (40) a pressure less than the external pressure to the container.