Twenty-First Century Water Commission Act of 2008

Twenty-First Century Water Commission Act of 2008 - Establishes the Twenty-First Century Water Commission to: (1) project future water supply and demand; (2) study current water management programs of federal, interstate, state, and local agencies and private sector entities directed at increasing water supplies and improving the availability, reliability, and quality of freshwater resources; and (3) consult with representatives of such agencies and entities to develop recommendations for a comprehensive water strategy.

Requires that such strategy: (1) identify incentives intended to ensure an adequate and dependable water supply to meet U.S. needs for the next 50 years; (2) consider all available technologies and other methods to optimize water supply reliability, availability, and quality, while safeguarding the environment; (3) recommend means of capturing excess water and flood water for conservation and use in the event of a drought; (4) suggest financing options; (5) suggest strategies to conserve existing water supplies, including recommendations for repairing aging infrastructure and promoting efficiency and conservation; and (6) include other objectives related to the effective management of the water supply to ensure reliability, availability, and quality.

Requires the Commission to submit interim and final reports to the President and to specified congressional committees. Terminates the Commission within 30 days after transmitting a final report. Authorizes appropriations.