Water has always had a special place among the production inputs of the agricultural sector, especially in arid and semi-arid regions, including Iran. In recent decades, with the increase in population and the need for more food, the supply of water required for agriculture has been through pressure on the country's water resources, and the expansion of agricultural activities has had an impact on both the quantitative and qualitative aspects of water. In this study, first, using the water footprint index; the green, blue and gray water footprints of wheat, barley and corn in Iran were calculated for the period 2002-2022. Then, to investigate the environmental effects of the production of these cereals, the decoupling index was used. The results of the study showed in wheat and barley, the share of green water was greater than blue and gray water, while in corn, the share of blue water was greater. The results of the decoupling index related to the relationship between yield and blue and green water consumption in wheat show that this index was in a strong decoupling and best possible state of decoupling in nine production periods, and the decoupling index of environmental pollution from wheat yield was in the worst state in 2012, 2017, 2019 and 2021. According to the results obtained, it is suggested that in line with the goals of sustainable development and sustainable food security, environmental protection policies and efficient water resource management should be considered simultaneously with policies to increase production and yield.