Corporate social responsibility (CSR) has today become an important phenomenon and most organizations spends substantial amount of funds on CSR activities. However, empirical evidence on what determine the amount spent on CSR activities by public water sector organizations in Tanzania is lacking. Thus, the current study focus on determining factors that influences CSR spending by public water supply and sanitation authorities in Tanzania. Quantitative data were collected from 2015 to 2019, and a Fixed Effect estimation technique with instrument variable was employed in the analysis. The study revealed that; the approved CSR budget size, revenue collection efficiency, financial leverage, and organization size significantly influence CSR spending. The study contributes to the existing CSR literature in the public sector, and provides inputs on policies formulation that aims to enhance CSR investment public sector organizations
