Any city of the second class may enter into any deeds of trust, indentures or other agreements with any bank or trust company or other person or persons in the United States having power to enter into the same, including any Federal agency, as security for such bonds, and may assign and pledge all or any of the revenues or receipts of the waterworks thereunder. Such deed of trust, indenture or other agreement may contain such provisions as may be customary in such instruments or as the city may authorize, including (but without limitation) provisions as to--
53 P.S. § 25686