Geospatial analysis of surface water and groundwater quality using GIS in Ishaka subcounty, Bushenyi District, Uganda.

Access to safe drinking water remains a major public health challenge in low- and middle-income countries, particularly in rapidly urbanizing peri-urban settings. This study assessed the spatial variability of physicochemical and microbiological water quality in Ishaka Subcounty, western Uganda, using field-based measurements integrated with Geographic Information Systems (GIS). A total of 49 water samples were analysed for physicochemical parameters (pH, electrical conductivity, total dissolved solids, total suspended solids, temperature, dissolved oxygen, and nitrates) and microbiological indicators (faecal coliforms and Escherichia coli). Spatial interpolation was performed using the Thin Plate Spline method. Results indicate that physicochemical parameters largely complied with WHO and Uganda National Bureau of Standards drinking-water guidelines, while microbiological contamination was widespread and spatially clustered. These findings demonstrate that microbial contamination poses the most significant public health risk despite generally acceptable chemical water quality. The study provides spatially explicit evidence to support targeted water safety interventions and public health planning in similar peri-urban environments.