Water Infrastructure Financing Act

Water Infrastructure Financing Act - Amends the Federal Water Pollution Control Act (commonly known as the Clean Water Act) to: (1) authorize the Administrator of the Environmental Protection Agency (EPA) to establish a competitive grant program to provide technical assistance to small and medium treatment works on wastewater and stormwater approaches; (2) expand the list of projects eligible for state water pollution control revolving loan fund (commonly known as the Clean Water State Revolving Fund or CWSRF) assistance; (3) provide assistance, including loan forgiveness, for disadvantaged communities; (4) allow states to forgive repayment of a portion of a loan for alternative approaches to wastewater and stormwater controls; (5) establish a priority system for providing financial assistance from the CWSRF; (6) allow a transfer of capitalization grants between revolving loan funds for water pollution control and safe drinking water treatment; (7) extend through FY2012 the authorization of appropriations for CWSRF; and (8) revise provisions concerning sewer overflow control grants, including by extending the authorization of appropriations for such grants through FY2012.

Directs the Administrator to establish a grant program for watershed restoration through the protection or improvement of water quality.

Amends the Safe Drinking Water Act to: (1) require the Administrator to develop an implementation plan for contaminant prevention, detection, and response and extend funding for such activities through FY2012; (2) establish a priority system for providing assistance to enable small public water systems to achieve and maintain compliance with national primary drinking water regulation; (3) require the Administrator to give grants to provide technical assistance for the design, operation, construction, and maintenance of household wells and small shared well-systems that provide drinking water; (4) expand the list of projects eligible for state drinking water treatment revolving loan funds (commonly known as the Drinking Water State Revolving Fund or DWSRF); and (5) extend the authorization of appropriations for the DWSRF through FY2012.

Directs the Administrator to: (1) establish a grant program to assist community water systems in meeting the requirements of the Safe Drinking Water Act; (2) authorize appropriations for lead service line replacement in the District of Columbia; (3) establish a grant program to research and develop the use of innovative and alternative technologies to improve water quality or drinking water supply; (4) establish a nationwide demonstration grant program for water quality enhancement and management; (5) provide capitalization grants to states for agricultural pollution control technology revolving funds; (6) identify ways to improve the state revolving fund review process; and (7) enter into an arrangements with the National Academy of Sciences for a cost of service study of public water systems and treatment works and a study on the management of water supply, wastewater, and stormwater in urban areas and surrounding communities.