A liquid flow regulator has a housing including an axial bore, an inlet, an outlet and a plurality of axial grooves opening endwise of the inlet and laterally of the housing into the bore. The grooves, which have different axial lengths, taper axially so that the cross-sectional area of each groove gradually decreases from the inlet to nothing at a point where the groove merges with the bore. An elastomeric stock fits within the bore. A plunger for expanding the sock radially outward into sealing engagement with the housing adjacent the bore is axially movable within the bore. Flow through the grooves and the bore is regulated by the axial position of the plunger and the minimum cross-sectional area of the tapered, axial grooves at the axial location where the sock seals the bore. Axial adjustment of the plunger sequentially opens and closes passage from the grooves through the bore to the bore outlet. The upper end of the plunger is provided with threads for engagement with internal threading in a passageway so that rotation of the plunger adjusts its axial position for control of the flow. The connection between the plunger and passageway threads is flexible so that the threads can be flexed out of engagement with each other when it is desired to axially and non-rotatively move the plunger to quickly place the regulator in a fully open or fully closed condition.