The MI is calculated as: MI = C / MAC (after Caerio et al., 2005). Where, C is the metal concentration (mg/l) in water sample and MAC (mg/l) is the maximum permissible limit of WHO (2018) for drinking water. Caerio et al., (2005) divided the metal index into six classes depending on purity. These classes are as follows:

1) Class I: very pure (MI6)

Best Regards Namat M. Hamed

Thanks a lot Osama Rahil