Comparative Evaluation of the Effectiveness of Basalt, Quartzite, and Granite Altérite in Purifying Polluted Surface Water in the City of Dschang, West Cameroon

Access to safe drinking water remains a major public health issue in low- and middle-income countries. Local geological materials offer an affordable alternative to costly conventional treatments. This study evaluates the effectiveness of basalt, quartzite, and granitic weathered rock in purifying surface water in western Cameroon. Materials collected in Dschang were crushed, sieved (0.3 mm), washed, and sterilized, then used to make gravity filters. Filtered river water was analyzed before and after treatment for physicochemical and bacteriological parameters according to APHA methods. Data were compared using the Kruskal-Wallis test (α = 5%). All materials reduced bacterial load and turbidity. Granitic alterationite performed best, with total elimination of fecal streptococci and Salmonella spp., and greater than 99% for Vibrio spp. A significant decrease in turbidity, conductivity, TDS, and nitrates was observed, while basalt showed a tendency to release ions. Granitic alterationite is the most effective material for making surface water drinkable. These results confirm the potential of local geological materials as simple and sustainable solutions for access to drinking water in resource-limited environments.