Evaluation of drinking water suitability in rural primary school environments: linking hydrochemistry, multivariate analysis, and water quality indices in Northern Uganda

ABSTRACT

A graphical abstract summarizing a groundwater quality assessment in Uganda. The figure begins with a map of Uganda indicating the study location. Arrows lead to an analytical framework showing key water quality parameters, including pH, total dissolved solids (TDS), major ions, and trace metals, analyzed using principal component analysis (PCA). A second panel presents hierarchical cluster analysis (HCA), and the results are integrated into a water quality index (WQI). The key findings identify groundwater as predominantly belonging to the calcium–magnesium–bicarbonate (Ca–Mg–HCO₃) hydrochemical facies, represented by a triangular hydrochemical diagram. A photograph of two children collecting water from a hand pump illustrates the importance of groundwater as a source of drinking water for rural communities. The figure summarizes the progression from study area identification and water quality analyses to hydrochemical characterization and water quality assessment.

Groundwater is the dominant source of drinking water in rural Sub-Saharan Africa, yet its suitability in school environments is rarely evaluated using process-based approaches. This study assesses groundwater sources used by government aided primary schools in Vurra Subcounty, Northern Uganda, integrating hydrochemical analysis with principal component analysis (PCA), hierarchical cluster analysis (HCA), and Water Quality Index (WQI) assessment. Water sources exhibited slightly acidic to near-neutral conditions (pH 5.59–7.17) and low mineralization (TDS: 4–356 mg L−1), consistent with dilute basement aquifers. PCA indicates that hydrochemical variability is primarily controlled by carbonate-mediated water–rock interaction (PC1: 41.0%), while redox-sensitive mobilization of iron and manganese accounts for secondary variability (PC2: 22.8%). WQI values ranged from 27.07 to 219.96, with 55% of sites classified as poor to very poor. Sites with elevated WQI values correspond to higher Fe and Mn concentrations rather than total dissolved solids. These results indicate that groundwater suitability in the study area is constrained by trace metal dynamics within an otherwise low-mineralization system. The findings highlight the need for targeted monitoring and treatment strategies that explicitly address redox-driven contaminants in rural water supply systems.