Water treatment facilities in South Africa are crucial for ensuring safe drinking water. However, their performance varies significantly across different regions. Panel data regression models were employed to analyse the impact of various variables on water yield efficiency. A significant positive relationship was observed between investment in infrastructure and water yield, with an estimated coefficient of $0.85$ (95% CI: [0.72, 0.98]). Investment in infrastructure is a key factor for improving water treatment facility yields. Funding should be directed towards upgrading existing facilities to enhance their performance.