Abstract: A discrete step, maximum flow-rate-selectable valve includes: (a) an entry tube with: (i) an exit with a single, off-center hole that lies on the circumference of a circle of radius “r” that is centered on the centerpoint of the exit, and (ii) an exterior surface having a portion with rotational symmetry, (b) a selector tube with: (i) an exit with a plurality of holes, each having a differing diameter and a center point that lies on the circumference of a circle of radius “r” which is centered on the centerpoint of the selector tube exit, and (ii) an interior surface configured to lie proximate said entry tube, exterior surface portion having rotational symmetry so as to assist in providing a water-tight seal between said tubes, and (c) a means to enable the selector tube to rotate in discrete steps around the entry tube.