Whenever an affidavit of non-responsibility has been filed with the City Treasurer as to certain premises, a deposit as set by the City Council, and amended by resolution from time to time, per residential single-family dwelling unit shall be made with the City Treasurer at the time of application for connection to the public sewer and water systems. This deposit shall be held as a guarantee of payment of all or any portion of the deposit for payment of any delinquent charges or later turn-on charges in the event services have been discontinued for nonpayment. The deposit not used for the payment of delinquent service charges shall be returned to the depositor upon discontinuance of service to the property or may be transferred to the credit of a future occupant by written request to transfer received from the depositor.