Kajiado County suffers from acute water scarcity caused by climate-driven droughts and surface-water deficits that severely threaten agro-pastoral livelihoods, forcing a reliance on groundwater extraction across unserved zones of Kajiado Central Sub-County. Weak regulatory oversight has led to uncoordinated, dense borehole clustering that causes localized static water tables to drop rapidly, while private water pricing strains household economies and unregulated extraction bypasses public health monitoring for hazardous geogenic fluoride. This study implements a comparative ex-post facto retrospective research design spanning a 10-year operational horizon (2015–2025) to evaluate the long-term performance of resource-efficient Solar Water Pumping Technology (SWPT) as an alternative to conventional diesel and grid regimes. Synthesizing Common-Pool Resource (CPR) and Socio-Technical Systems (STS) theories, the study relies entirely on archival secondary data sourced from the Kajiado County Ministry of Water, the Water Resources Authority (WRA), and public health registries, evaluated via statistical trend tracking and thematic analysis. The empirical findings reveal that while transitioning to solar water pumping lowers operational costs by 60%–75% compared to diesel, the zero-marginal cost of solar power creates an economic incentive for unrestricted over-pumping that accelerates aquifer drawdown, while the clean energy transition exhibits a major health compliance gap by routinely distributing untreated water that exceeds the WHO 1.5 mg/L fluoride threshold. Technical upscaling must be legally bound to institutional governance; this study provides an empirical baseline for the Kajiado County Government to enforce spatial drilling limits, embed solarized frameworks into t