Limitation of water in Iran has resulted in developing well-elaborated rules for water exploitation throughout the history. Forming traditional farming units (boneh) are stemmed from the reality that except in one or two areas, water is the scarcest agricultural resource in Iran. Three important sources of water in Iran have been the aqueducts (qanat), the rivers, and the springs respectively. Each of these sources has associated with a complex regulation of their use for irrigation. This exploitation system consists of managing the water supply, the water distribution and transfer, and finally, managing the water usage. However, regarding the changes in the Iranian rural community after Land Reforms and the Islamic Revolution, the disruption of traditional systems of agricultural production such as boneh, and abolishment of the Khans' and the landlords' rule, the irrigation systems, too, underwent certain transformations. These changes include forming ham-ab groups among the farmers, which re-organized the previous rules and systems of water distribution in a new framework and cooperated in optimum use of water and improvement of agricultural lands.