(a) Rates, fees, and charges for water service, sewer service, and fire protection service rendered by the authority from any of its water systems, sewer systems, or fire protection facilities shall be so fixed and from time to time revised as at all times to provide funds at least sufficient to:
(1) Pay the cost of operating, maintaining, repairing, replacing, extending and improving the systems and facilities, or either, from which such services are rendered;
(2) Pay the principal of and the interest on all bonds issued and obligations assumed by the authority that are payable out of the revenues derived from operation of those systems and facilities as the said principal and interest become due and payable;
(3) Create and maintain such reserves for the foregoing purposes or any of them as may be provided in any mortgage and deed of trust or trust indenture executed by the authority under this article or in any resolutions of the board authorizing the issuance of bonds, the assumption of any obligation, or the acquisition of any such system or facility; and
(4) Make such annual payments, if any, to the United States of America or any agency or instrumentality thereof, the state, municipalities, counties, departments, authorities, agencies, and political subdivisions of the state and any public corporations organized under the laws of the state as the authority may have contracted to make.
(b) The provisions of subsection (a) of this section shall apply to any authority organized under this article for the purpose of constructing and operating a sewer system, either separately or in combination with a water system or fire protection facility or both.