Each receipt for a cash deposit to establish or reestablish credit for water service will contain the following statement:

"This deposit may be applied to unpaid balances where service has been discontinued by the city because of nonpayment of bills. This deposit, less the amount of any unpaid water bills, will be refunded, without interest, on discontinuance of service, or after the deposit has been held for twelve consecutive months, provided service has been continuous, and all bills for such service have been paid."