Valve for the venting circuit of a liquid tank, the valve comprising a chamber which includes openings that allow liquid to penetrate into the chamber above a certain level in the tank and/or in the event of waves in the tank or the tank being turned upside down, a cover for the chamber including an aperture that is susceptible to open into the venting circuit of the tank, and a float comprising a body and a needle that close off the aperture, the float being able to slide vertically inside the chamber depending on the level of liquid therein, the needle of the float being frustoconical-shaped and based on an elastomeric material.