Rates, fees, and charges for water, sewer, or garbage service rendered by the authority from any of its systems 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 and obligations assumed by the authority that are payable out of the revenues derived from operation of those systems and facilities together with revenues from any tax sources and fees as the 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 assumption of any obligation or the acquisition of any such system or facility.
(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.