Method for loading a 3D flexible pouch in a storage housing of a rigid container of a predetermined depth, wherein the flexible pouch is adapted for filling with a biopharmaceutical product by means of at least one flexible supply line (9a, 9b), the container comprising an upper edge defining an upper transverse opening for access to the storage housing, the method comprising, prior to filling, the steps consisting essentially of: - extending the flexible pouch, in an initial non-filled state, along a given inner face of the storage housing, so as to define a lower end and an upper end which are arranged on either side of said upper transverse opening, wherein the upper end of the flexible pouch comprises at least one upper port (12a, 12b) to which said flexible supply line (9a, 9b) is connected, said upper port (12a, 12b) being arranged on a given face of the flexible pouch in its initial non-filled state; - maintaining the upper end outside of the storage housing; characterized in that the method further comprises the steps consisting essentially of: - providing a support surface on the rigid container, by means of at least one support device mounted along a determined side of the upper edge, - orientating and positioning the flexible pouch so that a first portion of the given face of the flexible pouch is face to face with the given inner face and so that a second portion of said given face of the flexible pouch is in contact with the support surface, such that said flexible supply line (9a, 9b) connects to the flexible pouch from underneath the support surface, and - before or during filling, inserting said flexible supply line (9a, 9b) into a slot that separates said support surface into two surface portions (22a, 22b), while keeping the second portion of the given face, which is part of the upper end of the flexible pouch, placed against the support surface, - during filling, guiding said supply line (9a, 9b) by a convex guide surface provided in the support device and extending between the two surface portions (22a, 22b), the guide surface covering a portion of the upper edge of the container and delimiting one end of the slot, whereby the supply line (9a, 9b) can be lifted above the upper edge during filling, when the upper end of the flexible pouch is moved into the storage housing. - extending the flexible pouch, in an initial non-filled state, along a given inner face of the storage housing, so as to define a lower end and an upper end which are arranged on either side of said upper transverse opening, wherein the upper end of the flexible pouch comprises at least one upper port (12a, 12b) to which said flexible supply line (9a, 9b) is connected, said upper port (12a, 12b) being arranged on a given face of the flexible pouch in its initial non-filled state; - maintaining the upper end outside of the storage housing; - providing a support surface on the rigid container, by means of at least one support device mounted along a determined side of the upper edge, - orientating and positioning the flexible pouch so that a first portion of the given face of the flexible pouch is face to face with the given inner face and so that a second portion of said given face of the flexible pouch is in contact with the support surface, such that said flexible supply line (9a, 9b) connects to the flexible pouch from underneath the support surface, and - before or during filling, inserting said flexible supply line (9a, 9b) into a slot that separates said support surface into two surface portions (22a, 22b), while keeping the second portion of the given face, which is part of the upper end of the flexible pouch, placed against the support surface, - during filling, guiding said supply line (9a, 9b) by a convex guide surface provided in the support device and extending between the two surface portions (22a, 22b), the guide surface covering a portion of the upper edge of the container and delimiting one end of the slot, whereby the supply line (9a, 9b) can be lifted above the upper edge during filling, when the upper end of the flexible pouch is moved into the storage housing.