The sewer rental charge shall be payable at the same time and place as water bills for the district in which the premises served are located. The agency authorized to collect water bills, currently in the City of Eastlake, is authorized to bill and collect the sewer rental charges, in addition to the established charges for water, and to include said sewer rental charges on the regular water bills. Such sewer rental charges shall be computed quarterly and shall be included as a separate item or charge on each quarterly water bill. The collecting agency shall include on such quarterly billings an additional charge, as established from time to time by the appropriate authority, per billing account, for the benefit of the collecting agency.