Table 2 shows the average, minimum, and maximum concentration values of heavy metals in the groundwater samples of Sari city. Then, in order to determine the status of water resources for drinking purposes, the concentration of each heavy metal was analyzed based on the WHO and U.S. EPA standards. The results showed that the concentration of Fe in water samples was in the range of 10–450 μg/L, with an average value of 110 ± 12 μg/L. The concentration of Cu in water samples was in the range of 1–44 μg/L, with an average value of 12.0 ± 0.5 μg/L. The concentration of Mn in water samples was in the range of 10–290 μg/L, with an average value of 39.0 ± 1.4 μg/L. The concentration of Zn in water samples was in the range of 1–43 μg/L, with an average value of 8.9 ± 0.8 μg/L. The concentration of Cr in water samples was in the range of 0.01–44.30 μg/L, with an average value of 13.76 ± 1.03 μg/L. The concentration of Pb in water samples was in the range of 1–7 μg/L, with an average value of 1.66 ± 0.02 μg/L. The concentration of As in water samples was in the range of 1–23 μg/L, with an average value of 4.26 ± 0.12 μg/L. Table 2 also shows that the average concentration of all seven heavy metals in all water samples was lower than the standard concentration recommended by the U.S. EPA and the WHO.