The commission shall devote all monies, derived from any source other than the issuance of bonds for purposes authorized by the laws of the State of Mississippi, to or for the payment of all operating expenses, including such items as are normally required of utilities for sales development; to or for the payment of all bonds and interest on outstanding revenue bonds, if any, of such systems; to or for the acquisition and improvement of the system contingencies; to or for the payment of all other obligations incurred in the operation and maintenance of the systems and the furnishing of service; to or for the creation and maintenance of a cash working fund or a surplus fund to be used for replacement, extension of systems, and emergencies. The balance of the revenues of said systems, if any, may be used for any other lawful municipal purpose and may be paid to the governing authorities of the municipality for distribution to the various municipal funds, or may be disbursed for said purpose by the said commission at the direction and request of the governing authorities of such municipality.