Any customer desiring to discontinue service shall notify the city in writing of such fact at least ten (10) days before the date when such service shall be discontinued. On giving the written notice, the customer shall not be responsible for water bills incurred after the date specified in the notice. Any credit balance in favor of the customer as a result of an advance payment of bills or a deposit will be refunded upon discontinuance of service. (1989 Code § 14-141)