Whenever any premises connected with the water supply system becomes vacant, and the owner thereof desires to have the rates remitted for the nonuse of water on the premises, he shall file with the authority, not earlier than the first nor later than the tenth day of any month, or other dates approved by the authority, a written notice, giving the date the premises were vacated. If upon inspection it appears that the premises were vacant during the preceding month and no water was used, the rates for the month will be remitted. No remission of rates will be made for a less period than one calendar month or without the notice prescribed herein. This section applies to premises supplied at a fixed or flat rate only. (Prior code § 18-10)