When the installation of the new water service connection is complete, the City Superintendent shall inform the Clerk/Treasurer of the cost of the hookup fee and installation and will submit an invoice for payment. In the event the actual cost shall be less than the deposit, the difference shall be paid to the applicant or deducted from the applicant’s utility bill. In the event the actual cost of installation and hookup fee shall be more than the deposit, the difference shall be paid by the applicant within 30 days of invoice date.