Illinois Statutes Chapter 220. Utilities § 5/9-220.2. Water and sewer surcharges authorized

(a) The Commission may authorize a water or sewer utility to file a surcharge which adjusts rates and charges to provide for recovery of (i) the cost of purchased water, (ii) the cost of purchased sewage treatment service, (iii) other costs which fluctuate for reasons beyond the utility's control or are difficult to predict, or (iv) costs associated with an investment in qualifying infrastructure plant, independent of any other matters related to the utility's revenue requirement. A surcharge approved under this Section can operate on an historical or a prospective basis.

(b) For purposes of this Section, “costs associated with an investment in qualifying infrastructure plant” include a return on the investment in and depreciation expense related to plant items or facilities (including, but not limited to, replacement mains, meters, services, and hydrants) which (i) are not reflected in the rate base used to establish the utility's base rates and (ii) are non-revenue producing. For purposes of this Section, a “non-revenue producing facility” is one that is not constructed or installed for the purpose of serving a new customer.

(c) On a periodic basis, the Commission shall initiate hearings to reconcile amounts collected under each surcharge authorized pursuant to this Section with the actual prudently incurred costs recoverable for each annual period during which the surcharge was in effect.