In addition to the power conferred by sections 6119.01 to 6119.42, inclusive, of the Revised Code, to construct sewers and levy assessments therefor, and in the absence or insufficiency of a plan provided for in section 6119.31 of the Revised Code, the board of trustees of a regional water and sewer district may provide a system of sanitary and/or storm water sewerage, herein referred to only as sewerage, for any part of the area included within the district. Such a plan shall be devised with regard to the present and prospective needs and interests of the area, and shall be confirmed by the board.