The city clerk shall prepare monthly billing of the charges made by the city for the collection of refuse and at the option of the city such charges may be billed on the statement for payment of water bills. All such bills shall be payable at the time water bills are due and shall be payable to the city clerk. In the event refuse service is provided for a residence or business or commercial establishment hereunder which is not billed for water, such customer shall be billed separately for such service by the city. (Prior code § 9-209)