Some part of Tehran city's drinking water is supplied by underground resources. According to the condition of the resources, consumption rate and different seasons' temperature the rate of underground water changes between20% to 40% of total required water of Tehran. At present 441 deep wells are operating and they approximately produce 14.5 m3/S capacity of water.
The main part of these wells are drilled in the main aquifer of Tehran plain with the average depth of 250 m and maximum depth of 300 m that each one has averagely the ability of producing about 120 m3/h and maximum 600 m3/h.
The distribution and dispersion of these wells in Tehran city is related to the quantity of aquifer in different parts, the water supply requirement of each area, accessibility to the water treatment plants, storage reservoirs and water transfer mains and other effective factors in designing water supply network.
Withdrawal water from all underground resources after quality controlling is led to reservoirs. After disinfection water is transferred to the distribution and consumption network.