The Drinking Water State Revolving Fund (DWSRF) programs aim to assist states in making project and set-aside eligibility determinations for ongoing program implementation. This handbook serves as a consolidated reference manual addressing emerging eligibility questions related to sustainability, resiliency, and contaminants of concern. It includes examples of funded projects that showcase the flexibility of the DWSRF program, encouraging states to explore innovative funding approaches to protect public health. The EPA is committed to collaborating with states to maximize the return on investments in water systems, which are crucial for safe drinking water delivery and local economies. The document emphasizes the importance of ensuring that funds are spent on eligible projects to maintain program integrity and public health protection.