Emergency Water Infrastructure Improvements Act of 2021 This bill provides financial support for water infrastructure. Specifically, the bill provides appropriations to the Environmental Protection Agency for grants under the drinking water state revolving fund program to address contaminants in drinking water, which may include the repair and replacement of water distribution system components. Additionally, the bill directs the Department of Commerce to provide a specified amount of funding to address contaminants in drinking water from unobligated amounts of certain funds provided for economic development assistance programs.