stem 12 by coupling the distributor downstream of a water pump due to the semi circular shape of rotor 17 the water entering tear shaped cut out 16 from main pipe stem 12 exits through the secondary nozzles 13 which are unblocked secondary nozzles 13 are preferably coupled by tubing or the like to a number of distinct locations rotor 17 is rotated slowly by shaft 19 of motor 20 as rotor 17 rotates particular secondary nozzles 13 become blocked or unblocked thereby producing flow through certain previously blocked secondary nozzles and stopping flow through previously blocked secondary nozzles in this manner water is distributed to the various distinct locations in a manner that varies over time motor 20 can be arranged to operate at any infinite variety of speeds and preferably is drivable at manually selectable speeds a continuously variable speed control or a stepwise variable speed control can be coupled electrically to the motor for this purpose low speed operation for example at 1 10 revolutions per minute rpm is most useful for the preferred applications discussed herein according to one potential application of the invention each of secondary nozzles 13 is coupled for example by tubing or hose to a sprinkler head in a farm field whereas constant watering in a limited area may overly saturate the ground and provide more water than can be used by the plants the invention allows automatic selection of a subset of the sprinklers for a predetermined time followed by selection of a different subset in arid areas such as the farmlands of california available water can be efficiently used a single sprinkler head connected to a secondary.