AbstractConcerns about scarcity of water have focused attention on irrigation, the largest water‐using sector worldwide, which is widely seen as a low‐value, wasteful and “inefficient” use for water. The terminology for this debate is, however, poorly defined – often failing even to distinguish between consumptive and non‐consumptive uses. In consequence, technical interventions have not always led to the expected, desirable outcomes, and the recommendations in many reports and papers are at best dubious, at worst simply wrong. The history of the analysis of “irrigation efficiency” is traced, and compared with the science of hydrology, which offers consistent terminology for various scales of analysis from field through irrigation scheme to region and basin. Based on the work of various previous writers, an analytical framework and associated terms are proposed to better serve the needs of technical specialists from all water‐using sectors, policymakers and planners in achieving more productive use of water and tracing the implications of interventions on other uses and users. ICID recommends that this terminology be used in the analysis of water resources management at all scales, and form the basis for its research papers and other published outputs. Copyright © 2007 John Wiley & Sons, Ltd.