Water treatment systems in South Africa have seen significant investment over recent decades to improve water quality and supply reliability. The analysis employs a fixed effects model (FE) with robust standard errors to account for unobserved heterogeneity across regions and over time. A notable trend observed was an increase in treated water volume by approximately 15% from to , driven by technological upgrades and policy interventions. The panel data approach reveals the necessity of continued investment and adaptive management strategies for sustainable yield improvements in South Africa’s water treatment systems. Investment should be directed towards upgrading older facilities and expanding coverage to underserved areas, while monitoring system performance through regular assessments. Water Treatment Systems, Panel Data Estimation, Yield Improvement, Fixed Effects Model The maintenance outcome was modelled as $Y_{it}=\beta_0+\beta_1X_{it}+u_i+\varepsilon_{it}$, with robustness checked using heteroskedasticity-consistent errors.