Seasonal Microbial and Physicochemical Variations in Shared Water Resources Within the Arid and Semi-Arid Southwestern Kenya Landscape

Water scarcity and poor access to potable water are growing concerns in sub-Saharan Africa. This study investigated seasonal variations in microbial contamination and physicochemical properties of surface waterpoints, the primary sources of water in southwestern Kenya, using a cross-sectional environmental surveillance design (May 2024-April 2025). Total coliforms and Escherichia coli isolates were quantified, to assess water safety and ecosystem health using membrane filtration and differential chromogenic agar. Results revealed high microbial contamination in all samples (100% for total coliforms; 62.5% for E. coli ), with significantly higher bacterial loads during the wet season. Total coliforms and E. coli averaged 1.13 × 10 6 CFUs/mL and 1.34 ± 1.26 × 10 5 ; and 2.84 × 10 5 CFUs/mL and 9.82 ± 9.78 × 10 4 , respectively, for wet and dry seasons respectively. Prevalence of E. coli in sampled sites was statistically significant between seasons ( χ 2 (1, N = 28) = 20.57, P < .05). Physicochemical parameters varied seasonally, with the dry season having higher pH, temperature, total dissolved solids and dissolved oxygen, while the wet season had higher conductivity. During the dry season, E. coli and total coliforms were not correlated while in the wet season, a weak but significant correlation existed ( r = 0.465, P = .003). Microbial parameters showed no significant correlation with physicochemical variables in either season, emphasising distinct seasonal interaction patterns. MANOVA conducted to assess the influence of water bodies, seasons and their interactions on microbial and physiochemical parameters revealed that water quality was significantly influenced by both water body type and season ( P < .001). Total coliforms were significantly influenced by season but not water sources. The presence of unsafe microbial loads and poor water quality highlights public health risks and potentially impact on livestock and livelihoods. These microscale findings, advocate for continuous ecological surveillance and public health monitoring on water quality status and community awareness. We recommend promotion of nature-based indigenous solutions for water and ecosystem management amid climate change.