Water has different physical characteristics as turbidity, color, TDS, etc. On the other hand, chemical characteristics of water such as alkalinity, acidity, and hardness can affect its quality. Physicochemical characteristic observation of groundwater resources, based on chemical analysis of the dry and wet period of 2016 and transferred to GIS software and analysis in quality observation has been done in Mamlou dam aquifer in Tehran (Iran). In this study, physicochemical parameters for 16 wells from 16 villages have been experienced. The parameters were: TDS, Cl, SO4, NO3, Ca, Mg, EC, F, HCO3-, pH, total hardness, turbidity, and Na. Finally, groundwater quality index or GWQI was calculated for each village in the dry and wet period of 2016 by just 7 parameters. The results showed that two villages in the research area had a serious problem with drinking water. GWQI for Garmabsard and Viraneh villages were respectively more than 140 and 100 in both dry and wet period of 2016, which shows the water is unsuitable for drinking in these two villages. TDS of the 2 villages are more than 1500 ppm, but they did not have any problem with Calcium and Magnesium. Other parameters such as turbidity follow a different trend and most of the time its problem is related to seasonal rainfall.
