70 ILCS 2805/20
The board of trustees of any sanitary district organized under the provisions of this Act, shall designate one or more banks or savings and loan associations in which the funds and moneys of the sanitary district in the custody of the treasurer or custodian of such district may be kept. When a bank has been designated as a depositary it shall continue as such until ten days have elapsed after a new depository is designated and has qualified by furnishing the statements of resources and liabilities as is required by this Act. When a new depository is designated, the board of trustees shall notify the sureties of the treasurer or custodian of that fact, in writing, at least five (5) days before the transfer of funds. The treasurer or custodian shall be discharged from responsibility for all such funds and moneys which he deposits in a depositary so designated while such funds and moneys are so deposited.
70 ILCS 2805/20