105 ILCS 5/32-7.1

The amount of the bond prescribed by Section 32-7 shall be fixed by the governing body of the district but shall not be less than 1/10 of the maximum amount of all moneys which came into the hands or control of such treasurer or his predecessors during any fiscal year in the preceding 5 years nor less than 1 1/2 times the largest amount estimated by such governing body will be in his hands or control at any one time if individuals act as sureties nor less than the largest amount estimated by such governing body will be in his hands or control at any one time if the surety is a surety company authorized to do business in this State.