The water drainage sieve is a single rotating sieve in perforated iron sheet which permits the water drainage from the product (shell fruit, in particular hazelnuts) once passed in the tank. This machine is installed after the tank, in the place of the perforated slide. This passage is useful to avoid that the water arrives in the dryers. It is endowed with a container for water recovery in which the immersion pump, supplied together with the tank, is installed. Suggested for systems of big dimensions.