Two measurements are used to evaluate how your sprinkler system performs: Application Rate and Distribution Uniformity (DU). The application rate is the average rate (usually expressed in inches per hour in the U.S.) that water is applied by an irrigation system. You can use the application rate to calculate how long to run your sprinklers to apply a specific amount of water. The DU measures the application of water in the driest areas as compared to the average. This is important because we want to water so that all of the grass is healthy. A system with a DU of 100% would be perfect. A system of 60% means that the application rate in the least watered 1/4 of your lawn is only 60% of the average. We use DU for scheduling to adjust the average application rate to get a modified application rate used for scheduling the length of irrigation,
Well designed home sprinkler systems have typical application rates and uniformity's shown in the table below. You can use these figures for scheduling, however it is recommended that you measure these values on your system.