Ohio Rev. Code § 6119.47
Notice of the passage of a resolution of necessity and the filing of the estimated assessments under section 6119.46 of the Revised Code shall, after the estimated assessments have been prepared and filed as provided by such section, be served by the secretary of the board of trustees of the regional water and sewer district, or a person designated by such secretary, upon the owners of the lots or parcels of land to be assessed for the proposed project, in the same manner as service of summons in civil cases, or by certified mail addressed to such owners at their last known addresses or to the addresses to which tax bills are sent, or by a combination of the foregoing methods. If it appears by the return of service or the return of the certified mail notice that one or more of the owners cannot be found, such owners shall be served by publication of the notice once in at least one newspaper having a general circulation within the district. The notice shall also set forth the place where such estimated assessments are on file and are open for public inspection. The return of the person serving the notice or a certified copy thereof or a returned receipt for notice forwarded by certified mail accepted by the addressee or anyone purporting to act for him shall be prima-facie evidence of the service of notice under this section.
R.C. § 6119.47