Ohio Rev. Code § 6119.40
The exercise of the powers granted by Chapter 6119. of the Revised Code, will in all respects be for the benefit of the people and for the increase of their prosperity and the improvement of their health and living conditions. The operation and maintenance of public works by the board of trustees of a regional water and sewer district constitute the performance of essential governmental functions. Such district shall not be required to pay any taxes or assessments upon any real or personal property acquired, owned, used, or controlled by it under Chapter 6119. of the Revised Code, or upon the income or gross receipts therefrom, and the bonds and notes issued under such sections and the transfer of income therefrom, including any profit made on the sale thereof, shall at all times be free from taxation within the state.
R.C. § 6119.40