Water use efficiency, WUE (yield per unit of water) at crop and farm level, needs to be improved to cope with the increasing water demand forecasted for 2025. At the regional and/or catchment scale, a coherent scheme for water resource use and environmental protection must be implemented. Approaching the WUE issue on a large scale opens various opportunities to improve water management (water storage and distribution, irrigation scheduling and technology). We used a crop growth model to compare different scenarios for water saving and irrigation efficiency in maize and wheat production. A simple economic calculation is included to quantify the gross income. The evaluation was performed in two Mediterranean areas with low (500 mm) and medium (750 mm) precipitation. The simulation results show that under reduced availability of irrigation water or increased water cost, non-irrigated crops and supplementary irrigation become more competitive. The break-even point between irrigated and non-irrigated crops emerges at a water price of about 0.35 € m-3, assuming 60 percent efficiency of water use; however, this value varies widely depending on environment, climate and the price of the grain.