55 ILCS 5/5-15020
Rates and charges for the use and service of the waterworks properties, or sewage facilities, or waste management facilities, as the case may be, acquired by any county shall be sufficient at all times to pay the cost of maintenance and operation, to pay the principal of and interest upon all revenue bonds issued under the provisions of this Division, to provide a reasonable depreciation fund as established pursuant to the provisions of the ordinance authorizing the issuance of any revenue bonds, and to maintain such other reserves and sinking funds as may be deemed necessary or desirable by the county for the payment of the bonds or the extension or improvement of the waterworks properties or, sewage facilities, or a combination thereof, or waste management facilities, as the case may be, and the holder of any bond or bonds or any of the interest coupon or coupons of any revenue bonds of any such county may in any civil action, mandamus, injunction or other proceeding enforce and compel the performance of all duties required by this Division and the covenants and undertakings set forth in any bond ordinance, including the making and collecting of sufficient rates and charges for the use or service of the waterworks properties, or sewage facilities, or a combination thereof, or waste management facilities, as the case may be, and the proper application of the income and revenue therefrom.
55 ILCS 5/5-15020