The small amount and undesirable temporal and special distribution of precipitation through the country of Iran, causes some deficits both quantitatively and qualitatively.

Some general statistics of water resources of Iran are gathered here for more information :

•      Average precipitation in Iran is a bout 251 mm annually, which is less than a quarter of the average of the world.
•    Iran (1648000 km^ 2 in area) is about 1.1 percent of the earth land, meanwhile owing 0.34 percent of renewable water resources of the world.
•     In 1955, water supplied per capita in Iran was about 6203 cubic meter so ranking this country at 52nd position among the 100 other countries. In 1990 water supplied per capita decreased to 2025 cubic meter and it’s position jumped to 67th. These statistics are expected to be 816cubic meter and 73rd  in year 2025. According to international criteria, less than 1000 cubic meter of supplied water means the critical situation.
•    Regarding statistics, among the neighbour countries, Iran has the least supplied water per capita.
•    These worrying figures imply the urgency of situation and serious attention should be considered to increase the efficiency of water use. On the other hand, considering the agricultural part of water consumption which is about 94%, and reminding the overall application efficiency in this part which is less than 30%, the additional attention will be necessary and urgent.
•    As mentioned above the average precipitation of Iran is 251 mm and when considering the area of the country (1648000 km^2), it will result in 413 billion cubic meter of water annually.
•    285 billion cubic meter of this amount will be lost due to evaporation. Adding 7 billion cubic meter of incoming water to these figures, shows the total amount of 135 billion cubic meter  for whole accessible water. (another figures says this amount to 110 billion cubic meter).