A controllable emitter of an irrigation apparatus including a drip line and a control station configured to control a pressure of pressurized fluid in the drip line is provided. The controllable emitter is disposable along the drip line and includes a container coupled to the drip line, the container being formed to define an interior and including an inlet through which the pressurized fluid is receivable in the interior from the drip line and an outlet through which the pressurized fluid is exhaustible from the interior, a piston, including a magnetic element, disposed at least partially in the container to occupy a position in accordance with the pressure of the pressurized fluid and a sensor configured to sense a position of the magnetic element and to communicate a sensed position to the control station.