(a) If district bonds payable wholly from revenue are issued, the board shall set the rates of compensation for water sold and services provided by the district. The rates must be sufficient to:
(1) pay the expense of operating and maintaining district facilities;
(2) pay the principal of and interest on the bonds when due; and
(3) maintain the reserve fund and other funds as provided in the resolution authorizing the bonds.
(b) If bonds payable partly from revenue are issued, the board shall set the rate of compensation for water sold and any other services provided by the district. The rate must be sufficient to ensure compliance with the resolution authorizing the bonds or the trust indenture securing the bonds.