60 ILCS 1/205-120
The township board of a township that owns a waterworks system or sewerage system or combined waterworks and sewerage system may sell or lease the system or a separable portion of the system for any term not to exceed 99 years when, in the opinion of the board, the property is no longer necessary, appropriate, required for the use of, profitable to, or for the best interests of the township. This power shall be exercised by an ordinance passed by at least a two-thirds vote of the members of the board. The property shall not be sold or leased, however, for a less amount than is necessary to amortize any outstanding bonds issued under this Article nor, in any event, at a less amount than the reasonable value of the property (or a reasonable return on the investment in the property in the case of a lease) as determined by an appraisal made at the direction of the board by a person or persons acquainted with valuations of those kinds of properties.
60 ILCS 1/205-120