A safety anti-reversing device for a bottom of a basin in a ground comprising: - a body comprising communicating openings for passage of a liquid, and - a flexible membrane supported by the body and deformable, from a closed configuration in which the flexible membrane closes said communicating openings in tight manner so as to prevent leakage flow from the basin to the ground, to a pass-through configuration in which a filling flow of the liquid toward the basin is enabled passing through the body via the communicating openings, wherein the flexible membrane comprises: - an annular shutter offset with respect to the communicating openings and swivelling between a closed-off position in which the annular shutter is applied in tight manner on the body, and an open position in which the annular shutter is away from the body, the closed-off position of the annular shutter corresponding to the sealed-off configuration of the flexible membrane, and the open position corresponding to the pass-through configuration of the flexible membrane, and - a closing portion that does not swivel with respect to the body, distinct from the annular shutter and covering the communicating openings so as to be able to hermetically close the communicating openings, in the sealed-off configuration, and to be moved away from the communicating openings by a thrust force of the liquid from the ground to the basin in the pass-through configuration, the closing portion and the annular shutter forming part of the same wall under which the filling flow of the liquid can pass from the communicating openings to a level of a free edge of the annular shutter, when the flexible membrane is in the pass-through configuration. - a body comprising communicating openings for passage of a liquid, and - a flexible membrane supported by the body and deformable, from a closed configuration in which the flexible membrane closes said communicating openings in tight manner so as to prevent leakage flow from the basin to the ground, to a pass-through configuration in which a filling flow of the liquid toward the basin is enabled passing through the body via the communicating openings, - an annular shutter offset with respect to the communicating openings and swivelling between a closed-off position in which the annular shutter is applied in tight manner on the body, and an open position in which the annular shutter is away from the body, the closed-off position of the annular shutter corresponding to the sealed-off configuration of the flexible membrane, and the open position corresponding to the pass-through configuration of the flexible membrane, and - a closing portion that does not swivel with respect to the body, distinct from the annular shutter and covering the communicating openings so as to be able to hermetically close the communicating openings, in the sealed-off configuration, and to be moved away from the communicating openings by a thrust force of the liquid from the ground to the basin in the pass-through configuration, the closing portion and the annular shutter forming part of the same wall under which the filling flow of the liquid can pass from the communicating openings to a level of a free edge of the annular shutter, when the flexible membrane is in the pass-through configuration.