A fitting is provided which is intended to be inserted into a water pipe to supply irrigation water in controlled limited amounts to the root zone of plants. The fitting consists of a hollow cylinder with an inlet hole located in the center of one end of one cylinder and an outlet hole located in the center of the other end. The diameter of the entrance and outlet holes are considerably smaller in diameter than the hollow cavity within the cylinder and they are all located coaxially over the same centerline. The inner wall of the cavity on the outlet end of the cylinder is conical in shape in such a way that a flat resilient disc held lightly against this face will be in contact with the face only around its circumference. Additional pressure across the face of the disc will cause the disc to deform into the conical face which forms a seat for the disc. When water pressure is applied to the fitting a pressure differential across the disc results and the disc is forced against its seat and would seal the outlet hole and prevent water from passing if the surface of contact were smooth. However, these surfaces are textured so that water can seep across the seat in a multiplicity of restricted paths and flow out the outlet hole. The amount of water flow at any one pressure is determined by the size and shape of the textured pattern. When the water is turned off the disc pulls away from its seat and returns to its original flat shape and when water is again turned on, a small amount of water becomes entrapped in the seat area and as pressure builds up, the entrapped water is extruded out of the seat area through the outlet hole, flushing any solids that may tend to clog the restricted paths.
