Revenue bonds issued under this Division 139 shall be payable solely from the revenue derived from the operation of the combined waterworks and sewerage system on account of which the bonds are issued; provided, that bonds issued under this Division 139 may also be payable from funds pledged by the municipality issuing such bonds pursuant to the Illinois Finance Authority Act. Notwithstanding any such pledge or any other matter, these bonds shall not in any event constitute an indebtedness of the municipality within the meaning of any constitutional or statutory limitation and it shall be so stated on the face of each bond.
65 ILCS 5/11-139-7