Amends Section 4013 of the Water Infrastructure Improvements for the Nation Act (codified at 43 U.S.C. 390b) by (1) striking the terminal "and" in paragraph (1); (2) replacing the word "in" with "under" in paragraph (2); (3) redesignating existing paragraph (2) as paragraph (3); and (4) inserting a new paragraph (2) that lists sections 4009(c), 4010(b)(2), and subsections (a), (b), (c), (d), and (f) of section 4011 and provides that those provisions "shall expire 15 years after that date of enactment."

Amends 43 U.S.C. 3205 by (1) redesignating existing subsection (a) paragraphs (1)–(4) as (2)–(5) and inserting a new paragraph (1) defining “construction” by reference to subsection (f) of section 4011 of the Water Infrastructure Improvements for the Nation Act; (2) replacing subsection (b) to expand the program to provide grants for development of feasibility studies in addition to planning, design, and construction; (3) modifying subsection (d)(4) (text of the change not provided in the section); (4) amending subsection (k) to revise paragraph (1) and add an exception that paragraph (1) shall not apply to an eligible project that is under construction as of the termination date described in that paragraph; and (5) adding subsection (l) authorizing appropriations of $450,000,000 for fiscal years 2028 through 2032.

Replaces paragraph (1) of 43 U.S.C. 390h(g) to set a new authorization of appropriations for carrying out the section.

Replaces the numeric ceiling in 43 U.S.C. 390h-13(d)(1) with a $50,000,000 ceiling expressed in December 2025 prices and specifies an automatic annual CPI-based adjustment each January.