A device for dispersing a water-soluble polymer in powder form having a standard particle size of less than 1 mm, comprising: - a wetting chamber, into which the polymer is dosed, comprising a cylindrical upper part with a vertical axis of revolution extended by a conical lower part, said wetting chamber being further provided with: o at least one opening formed in the thickness of the wall of the upper and/or lower parts, said opening emerging laterally into a means for connection to a primary water supply circuit, ∘ a cover provided with an opening formed in the thickness of the wall of said cover, said opening emerging into a means for connection to a source of powdered polymer, - a chamber for grinding and discharging the dispersed polymer with a horizontal axis of revolution, said grinding chamber comprising: • a rotor driven by a motor and provided with blades, said blades possibly being inclined with respect to the horizontal plane of the stator, • a fixed stator in the form of a cylinder, in the wall of which a single row of vertical slots is cut over part of the height of said wall, the width of the slots of the stator advantageously being between 150 and 700 microns, • over all or part of the periphery of the chamber, a ring fed by a secondary water circuit, the ring communicating with the grinding chamber so as to spray pressurized water onto the stator, - a means for connecting the wetting chamber to the grinding chamber in the form of an L-shaped tube, one end of which connects to the lower end of the wetting chamber and the other end of which connects to the inlet of the grinding chamber, characterized in that the upper and lower parts of the wetting chamber and the L-shaped tube have an internal surface with an identical surface tension, and in that the cover of the wetting chamber has an internal surface with a surface tension higher than. - a wetting chamber, into which the polymer is dosed, comprising a cylindrical upper part with a vertical axis of revolution extended by a conical lower part, said wetting chamber being further provided with: o at least one opening formed in the thickness of the wall of the upper and/or lower parts, said opening emerging laterally into a means for connection to a primary water supply circuit, ∘ a cover provided with an opening formed in the thickness of the wall of said cover, said opening emerging into a means for connection to a source of powdered polymer, o at least one opening formed in the thickness of the wall of the upper and/or lower parts, said opening emerging laterally into a means for connection to a primary water supply circuit, ∘ a cover provided with an opening formed in the thickness of the wall of said cover, said opening emerging into a means for connection to a source of powdered polymer, - a chamber for grinding and discharging the dispersed polymer with a horizontal axis of revolution, said grinding chamber comprising: • a rotor driven by a motor and provided with blades, said blades possibly being inclined with respect to the horizontal plane of the stator, • a fixed stator in the form of a cylinder, in the wall of which a single row of vertical slots is cut over part of the height of said wall, the width of the slots of the stator advantageously being between 150 and 700 microns, • over all or part of the periphery of the chamber, a ring fed by a secondary water circuit, the ring communicating with the grinding chamber so as to spray pressurized water onto the stator, • a rotor driven by a motor and provided with blades, said blades possibly being inclined with respect to the horizontal plane of the stator, • a fixed stator in the form of a cylinder, in the wall of which a single row of vertical slots is cut over part of the height of said wall, the width of the slots of the stator advantageously being between 150 and 700 microns, • over all or part of the periphery of the chamber, a ring fed by a secondary water circuit, the ring communicating with the grinding chamber so as to spray pressurized water onto the stator, - a means for connecting the wetting chamber to the grinding chamber in the form of an L-shaped tube, one end of which connects to the lower end of the wetting chamber and the other end of which connects to the inlet of the grinding chamber,