; or (2) provide grant funds to another eligible entity to carry out a water efficiency incentive program described in paragraph (1). (e) Minimum requirement An eligible entity receiving a grant under the grant program shall use not less than 40 percent of the amount of the grant to provide water-efficient upgrades to low-income households. (f) Cost share (1) In general Subject to paragraph (2), the Federal share of the cost of carrying out a water efficiency incentive program using a grant awarded under the grant program shall not exceed 80 percent. (2) Waiver The Administrator may increase the Federal share under paragraph (1) to 100 percent if the Administrator determines that an eligible entity is unable to pay, or would experience significant financial hardship if required to pay, the non-Federal share. (g) Supplement, not supplant Amounts provided under a grant under the grant program shall be used to supplement, and not supplant, other Federal, State, local, or Tribal funds made available to carry out water efficiency incentive programs. (h) Authorization of appropriations (1) In general There is authorized to be appropriated to carry out this section $50,000,000 for each of fiscal years 2024 through 2028. (2) Administrative costs Of the amounts made available under paragraph (1) each fiscal year, the Administrator may use not more than 4 percent to pay the administrative costs of the Administrator. 4. Sustainable water loss control program (a) Technical assistance and grant program The Administrator shall establish and carry out a program (referred to in this section as the program )— (1) to make grants and provide technical assistance to eligible entities to perform annual audits of public water systems that are— (A) conducted in accordance with the procedures contained in the manual published by the American Water Works Association entitled M36 Water Audits and Loss Control Programs, Fourth Edition (or any successor manual determined appropriate by the Administrator)