(5) Evaluation of groundwater quality

According to the Groundwater Quality Standard (GB/T 14848-2017) [28], groundwater quality is divided into five levels (I~V). Groundwater at levels I~III can be used for domestic drinking, groundwater at level IV can be used for drinking after proper treatment, and groundwater at level V is not suitable for drinking. Taking level III as the standard (Table 1), if the concentration of the evaluated index is inferior to level III, it means that the index

is over the standard. When comprehensively evaluating the groundwater sample, the determination of the evaluated level obeys the inferior principle [28].


**Table 1.** Evaluated standard of the main indices of groundwater.

Level III: Level III of Standard for Groundwater Quality (GB/T 14848-2017); Units: pH is unitless, the other indices have units of mg/L; the nitrogen species were expressed as N to be consistent with the Groundwater Quality Standard; Fe represents the total iron; Mn represents the total manganese.
