Water Data Act This bill requires federal departments and agencies involved in water resources management to jointly develop and implement a National Water Data Framework and establish an interagency council, advisory committee, and grant program. Specifically, the bill requires the departments to jointly develop and implement a National Water Data Framework for integrating, sharing, and using water data to support water resources management and access. The departments must (1) develop and adopt common national standards for water data, (2) integrate water data and tools through common approaches to data infrastructure and platforms, and (3) harmonize and align water data policies and programs. The bill further requires these departments to establish an interagency Water Data Council to support the development and implementation of the framework. The bill also requires the Department of the Interior to establish an Advisory Committee on Water Information to advise Interior, the departments, and the council on the framework. The advisory committee members must include those involved in water-related activities across different sectors (e.g., state and local governments, Indian Tribes, water agencies, private sector entities, and nonprofit organizations). Finally, the bill requires Interior to establish a Water Data Grant Program in coordination with the council for nonfederal entities to carry out the purposes of this bill.