A filler head for a storage system includes a body to be mounted inclined having a main part closed by a cover part forming a cavity in which a separating device is received. The filler head is configured to receive, in a cylindrical wall of the separating device, a distribution nozzle of a fluid with an automatic stop sensor to prevent overfilling of the filler head. The filler head includes a buffer volume in one-piece with the main part in a back portion of the body reducing the speed of flow coming from the venting line, and the cylindrical wall includes a recess facing the opening of the buffer volume in the back portion of the body.