Rates, fees, and charges for water service rendered by the authority from any of its systems shall be fixed and periodically revised so as to provide at all times funds sufficient to:
(1) Pay the cost of operating, maintaining, repairing, replacing, extending, and improving the systems from which services are rendered.(2) Pay, upon becoming due and payable, 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 and revenues from any tax sources and fees.(3) Create and maintain reserves for the foregoing purposes as may be provided in any mortgage, 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 of the acquisition of any system.(4) Make annual payments, if any, that the authority has contracted to make, to the United States of America or an agency or instrumentality thereof, the state, municipalities, counties, departments, authorities, agencies, political subdivisions of the state, or any public corporation organized under the laws of the state.Ala. Code § 45-30-250.08 (1975)