Iran is located in an arid, semi-arid region. The mean annual precipitation of our country is about 250 mm which is less than the mean annual precipitation of Asia and about one third mean annual precipitation of the world. different kinds of climatic, topographic and geographic conditions, uneven distribution of surface streams are the hydrological features in many parts of the country. Iran possesses 37000 Qanats. These Qanats are providing 7 billion cubic meters water a year for agriculture productivities without consuming any kind of fossil fuel or electricity power. In recent years, increasing population has caused more demanding for new water sources such as digging new wells from aquifers, and this leads to accelerate decline in groundwater table. Decline in groundwater table has caused lots of problems, for instance increased number of arid fields, reduced the flow rate of rivers and lakes, decreased the quality of water, increased pumping costs, and the land subsidence. In this article, essential safety requisition and reconciliation of Qanats was studied by investigating the role of Qanats and comparing them with others sources.