Given the strategic remarkable rank of pistachio in non-oil exports, inputs’ management in its production is so important. As the scarcest input in agricultural sector, water is considered to be among the most important inputs of pistachio production. Water inadequate supply and climate conditions increase water demand in pistachio growing areas. It is necessary to determine the real value or price of water for establishing a balance between its demand and supply. Therefore, this study has aimed at estimation of water economic value. The method used in this research is the production function approach. Requested data sets were obtained from the questionnaires was filled out for crop years of 2013-2014. The results show that the average economic value of irrigation water is 50360 RLS but the average price paid by farmers is 1771 RLS per cubic meter of water. Thus, there is a wide gap between water value and the price paid by farmers with which appropriate pricing of water based on its economic value can be eliminated.