Drinking water quality assessment using water quality index and geostatistical techniques, Mardan District, Khyber Pakhtunkhwa, Pakistan

In this study, the Water Quality Index (WQI) was calculated for drinking water samples collected from an area of Mardan district. A total of 30 water samples were collected from water distribution systems at the end user end. The samples were analyzed for 21 parameters namely, C, pH, EC, Do, TDS, NTU, TH, Ca, Mg, Na, K, SO4, NO3, Mn, Cu, Fe, Zn, Pb, Ni, Cd and Cr. Standard methods were used for the analysis of the physicochemical parameters while heavy and trace metals from analyzed using Atomic Absorption Spectrometer. For the calculation of Water Quality Index, all parameters were subjected to screening using principal component analysis, thus reducing the original number of parameters to a final list of ten. The final list of parameters was used to calculate and map WQI. Moreover, two methods of kriging Ordinary Kriging and Empirical Beysian Kriging were compared for their performance in modelling the spatial distribution of the selected parameters in the study area. It was found that EBK performance was more appropriate as compared to other spatial variability models for the majority of the variables.