While any bonds are outstanding, the governing body of the district shall fix, maintain, and collect for services furnished or made available by the disposal system rates and charges adequate to:
(1) pay maintenance and operating costs of and expenses allocable to the disposal system;
(2) pay the principal of and interest on the bonds; and
(3) provide and maintain the funds created by the resolution authorizing the bonds.
Official text of the Texas Water Code as published by the Texas Legislative Council.