The importance of groundwater extends to both the current and future generations as an essential resource. The objective of this review is to apply a meta-analysis consisting of almost two decades of groundwater geochemistry characteristics in Iran. The results show the overall mean of 7.61 and 2106.6 μS cm 1 for pH and electrical conductivity (EC), respectively. The overall mean of cations and anions decreases in the following order (mg l 1): sulfate (SO4) (334.0) > chloride (Cl) (327.2) > sodium (Na) (247.2) > bicarbonate (HCO3) (236.7) > calcium (Ca) (118.3) > magnesium (Mg) (57.1) > carbonate (CO3) (24.0) > nitrate (NO3) (20.2) > potassium (K) (5.3). All parameters in groundwater were higher than the background level, indicating anthropogenic activities are intensively affecting the quality of groundwater in Iran. Generally, the north and northwest provinces presented a lower overall mean compared to the center, south, and east provinces in terms of groundwater quality. Decreasing agricultural and industrial activities, as well as proper land-use planning, are practices necessary to perform in the center, south, and east regions of Iran in order to improve groundwater quality.
