As part of water reform in the Murray–Darling Basin (MDB), water is being reallocated from irrigated agriculture to the environment. The adoption of on-farm water use efficient (WUE) measures is one way irrigators might adapt and remain viable. There has been limited evaluation of the potential of WUE measures for irrigators' adaptation. This paper addresses that gap by bringing together results from a case study in the Southern MDB and published results for the Northern MDB. Responses from irrigator surveys were used to determine the current and future intention to adopt existing WUE measures and then calculate the potential reduction in irrigation water applied. A moderate estimate suggests that about 10% less irrigation water can be applied. What this will mean for entitlement cuts under the Basin Plan will depend on how return flows (i.e. excess irrigation water previously contributing to surface and groundwater) are accounted for. These results suggest that irrigators in the MDB are willing to adapt to some reduction in water availability. This information should contribute to debate about water reform impacts on irrigators and their communities, but those managing the MDB must take into account that on-farm WUE gains may lead to reduced return flows.