Evaluation of Tehran city groundwater quality by WHO water quality index

In order to determine the groundwater quality of Tehran city in 2010 and 2011, seventy one wells were considered for water sampling. The groundwater quality was evaluated using WHO index and the quality was worse in 2011 in comparison with 2010.Furthermore, eastern and southern areas show more index values which indicate the lower groundwater quality for drinking use. According to the results gained in both years, the majority of northern sampling stations lie within the good range while the ones in southern areas are mostly addressed as poor quality. Uncontrolled water discharge, regular droughts as well as leakage of anthropogenic pollutants like NO3- and SO4— may be addressed as the major causes of groundwater quality degradation within the study area. Regarding the remarkable weight of NO3 in index quality interpretation, the key role of this pollutant in groundwater quality determination is manifested. Such quality degradation trend may reach a critical status in near future and should be seriously taken into consideration.