Indexing Approach for the Evaluation of Heavy Metals in Drinking Water Produced by a Moroccan Water Treatment Plant

In the present work, the assessment of drinking water quality was carried out through a monitoring of heavy metals in the treated and consumed waters in the city of Fes (Morocco). Monthly sampling was conducted for a period of 24 months between January 2016 and December 2019. Nine parameters were evaluated: pH, T (degrees C), Turbidity (NTU), Al, Fe, Cu, Mn, Al-2(SO4)(3) and CaO. Indexing approaches have been applied by calculating the Heavy Metal Pollution Index (HPI) and Metal Index (MI) for the assessment of influence of heavy metals on the overall quality of water. The obtained results for heavy metals are in good agreement with World Health Organization (WHO) standards. Though the aluminum concentration remains in the limits set by WHO, yet it shows a major contribution in the indices. This has been verified by the statistical analysis which demonstrates fair correlations between aluminum, HPI (r = 0.9) and MI (r = 0.77). Aluminum showed the important influence of seasonal change in the year as well as the doses of reagents injected during the treatment process on the concentration of aluminum is detailed.