Irrigation water use efficiency, the small size of the orchards, and part-time farmers aremajor issues for Spanish citriculture. How should irrigation water use efficiency be assessed? Doesirrigation water use efficiency improve when increasing the size of the orchards?  Are full-timefarmers more efficient in irrigation water use than part-time ones? To address these three questions,we propose to apply a new multicriteria approach based on the analytic hierarchy process (AHP)technique and the participation of a group of experts. A new synthetic irrigation efficiency index(IEI) was proposed and tested using data from an irrigation community (IC) and a cooperative offarmers in the East of Spain. The results showed that the size of the orchards had no relation withthe IEI scoring but full-time farmers tended to have better IEI scores and, thus, were more efficient.These results were obtained from a sample of 24 orchards of oranges, navelina variety, growing ina very similar environment, and agronomical characteristics. The proposed methodology can be auseful benchmarking tool for improving the irrigation water management in other ICs taking intoaccount the issues related to farm data sharing recorded during the case study.