Valve device that can be positioned in a pipe used for the passage of domestic wastewater, said pipe comprising: • a main duct whose internal surface delimits a passage for the flow of wastewater from an inlet opening to an outlet opening of the pipe, and • an inspection neck extending from the main duct in a transverse direction thereto, the inspection neck being provided with a longitudinal hole and an internal wall that radially delimits said hole, the hole defining an access opening to the passage of the main duct, said valve device comprising: • a shutter, • a fixing element arranged to be connected to the inspection neck in order to hold the shutter in the passage of the main duct between the inlet opening and the outlet opening of the pipe, • said shutter being movable between a first configuration in which said shutter is shaped to occlude the passage of the main duct so as to substantially prevent the flow of gaseous fluids from the outlet opening towards the inlet opening of the pipe, and a second configuration in which said shutter leaves the passage of the main duct sufficiently free for the wastewater to flow from the inlet opening to the outlet opening of the pipe, wherein said valve device comprises a main body made of a elastically deformable material that at least partly defines the shutter, said main body at least partially occluding the passage of the main duct when the shutter is in said first configuration so that a pressure exerted by the wastewater on said shutter causes a reversible elastic deformation of said main body that urges said shutter to move from said first configuration to said second configuration, wherein said fixing element is intend to be inserted in the hole of the inspection neck, said fixing element comprising a perimetric surface and being arranged so as to interfere with the internal wall of the inspection neck by means of said perimeter surface in order to hold said valve device in the pipe in a desired position, characterised in that said fixing element is shaped so that said perimetric surface interferes by friction with the internal wall of the inspection neck in order to hold said shutter in the passage of the main duct, said valve device being held in the main duct by a coupling between said fixing element and the internal wall of the inspection neck which is ensured by the shape thereof. • a main duct whose internal surface delimits a passage for the flow of wastewater from an inlet opening to an outlet opening of the pipe, and • an inspection neck extending from the main duct in a transverse direction thereto, the inspection neck being provided with a longitudinal hole and an internal wall that radially delimits said hole, the hole defining an access opening to the passage of the main duct, • a shutter, • a fixing element arranged to be connected to the inspection neck in order to hold the shutter in the passage of the main duct between the inlet opening and the outlet opening of the pipe, • said shutter being movable between a first configuration in which said shutter is shaped to occlude the passage of the main duct so as to substantially prevent the flow of gaseous fluids from the outlet opening towards the inlet opening of the pipe, and a second configuration in which said shutter leaves the passage of the main duct sufficiently free for the wastewater to flow from the inlet opening to the outlet opening of the pipe,