Reservoirs for fuel tanks, which can be filled via an opening that can be closed by a closing element, are already known. Such a closing element interacts with a sealing seat and is arranged on a bearing that is located in the region of the opening and is fixed to an edge area of the opening by at least two struts. In prior art, the opening, with the bearing and the struts, is often produced as a single-piece together with the reservoir and the base by injection molding. A disadvantage thereof is that the struts can undergo material shrinkage during production, which leads to a tension of the struts between the edge area of the opening and the bearing. This can lead to an irregular deformation and hence to an uneven sealing seat, so that the closing element does not seal in a tight manner and that the valve has a leak. in the reservoir according to the invention, the sealing of the opening is improved by at least one strut not having a rectilinear form, thus obtaining elastic expansion compensation.