A subsurface emitter includes a piston valve both preventing water from draining from the system, and blocking the entry of roots and soil into the emitter body. A nozzle is present at one or both ends of a vertical tube. A piston is held in a normally closed position by a spring in the absence of water pressure, covering ports in the nozzle. When sufficient water pressure in provided, the spring is compressed and the nozzle uncovers the port providing a subsurface spray of water. The spray of water is sufficient to clear mineral deposits which otherwise may accumulate and block the port.