Ohio Rev. Code § 6117.46: County trunk or main sewers.

When the director of environmental protection finds that a trunk or main sewer is necessary in a county for sanitary purposes, the board of county commissioners of such county may make surveys thereof and prepare plans and specifications thereof. Upon approval by the director of such plans and specifications, the board may construct and maintain said trunk or main sewer or part thereof within or without the limits of a municipal corporation, regulate the tapping thereof by lateral sewers, and prescribe the conditions of such tapping.