WIFIA Improvement Act of 2020 This bill allows certain federal water infrastructure loans to have maturity dates of up to 55 years. For a secured loan for a water infrastructure project with a useful life of more than 35 years, the final maturity date of the loan shall be no later than the earlier of (1) 55 years after the project's substantial completion, or (2) the useful life of the project. Currently, the latest possible maturity date of for this type of loan is 35 years from the project's substantial completion.