The efficiency of an irrigation system is a measure of how uniformly water is applied across the irrigated area. It is not possible for an overhead sprinkler irrigation system to apply water perfectly evenly. While properly designed sprinkler irrigation systems have sprinklers installed at spacings that result in optimum uniformity, wind, incorrect operating pressure, and nozzle wear or blockage can distort application patterns and reduce uniformity of water application. The grower’s aim is to maintain the irrigation system such that the uniformity of water application meets an acceptible standard.
The Distribution Uniformity (DU) is often used a measure of irrigation uniformity. See Testing irrigation uniformity.