The main purpose of this legislation is to improve the management and funding of alternative water source projects in the United States. It aims to enhance the country's ability to address critical water supply needs, particularly in the face of challenges such as drought and water scarcity. The bill seeks to amend the Federal Water Pollution Control Act to create a more robust grant program for these projects. Key provisions of the legislation include changing the terminology from "pilot program" to "grants," which indicates a shift towards a more established funding mechanism.