This document summarizes the Asian Development Bank's handbook for the economic analysis of water supply projects. The handbook provides guidance on conducting economic analyses for water supply projects, covering topics such as demand analysis, identifying least-cost alternatives, financial and economic analyses, identifying and valuing costs and benefits, and assessing distributional impacts and poverty reduction. It emphasizes the importance of economic analysis in justifying water supply projects and ensuring resources are optimally allocated. The handbook is intended to guide professionals in properly planning, preparing, and evaluating proposed water supply projects.