70 ILCS 5/8.08

To borrow money and to issue bonds, notes, certificates, or other evidences of indebtedness for the purpose of accomplishing any of said corporate purposes, which obligations may be payable from taxes or other sources as provided in this Act; and to refund or advance refund any of the foregoing with bonds, notes, certificates, or other evidences of indebtedness, which refunding or advance refunding obligations may be payable from taxes or from any other source; subject, however, to a compliance with any condition or limitation set forth in this Act or otherwise provided by the constitution of the State of Illinois.