Ohio Rev. Code Ann. § 735.30

When water works and electric light plants, or either of them, are owned and operated by a village which receives its street lighting and fire protection therefrom, and the proceeds from the operation of such plants are insufficient to pay the expenses of their operation, the legislative authority thereof may levy a tax not to exceed five mills on each dollar valuation of the taxable property, real and personal, listed for taxation in such village, to pay the running expenses and extensions made thereto after applying the proceeds therefrom. Such tax shall be in addition to all other taxes authorized by law.