This bill amends the Federal Water Pollution Control Act (commonly known as the Clean Water Act) to revise and reauthorize through FY2021 a grant program for intercepting, transporting, controlling, or treating combined sewer overflows or sanitary sewer overflows. The bill: (1) expands the grant program to include support for measures that manage, reduce, treat, or recapture stormwater or subsurface drainage water; (2) allows local or regional authorities to receive grant funds; and (3) increases the federal cost-sharing requirement by requiring the federal share of the costs of a project carried out using grant funds to be at least 75% of the total costs of the project.

The bill also revises the Clean Water Act by establishing requirements concerning managing water pollution during periods of heavy precipitation, including by requiring the Environmental Protection Agency (EPA) to establish a green infrastructure portfolio standard, which contains voluntary goals for increasing the percentage of annual water managed by eligible entities that use green infrastructure. (Green infrastructure is an approach used to manage stormwater by capturing stormwater in vegetation or porous surfaces.)

The EPA must update the guidance entitled "Combined Sewer Overflows - Guidance for Financial Capability Assessment and Schedule Development" to ensure that the evaluations of community financial capability and schedule development meet specified criteria.