Whenever the corporate authorities of any municipality determine to purchase or construct waterworks under the provisions of this Division 130, they shall have an estimate made of the cost thereof and, by ordinance, shall provide for the issuance of revenue bonds under the provisions of this Division 130. The ordinance shall set forth a brief description of the contemplated purchase or construction, the estimated cost thereof, the amount, rate of interest, time and place of payment, and other details in connection with the issuance of the bonds. The bonds shall bear interest at not more than the maximum rate authorized by the Bond Authorization Act, as amended at the time of the making of the contract, payable semi-annually, and shall be payable at such times and places not exceeding 20 years from their date as shall be prescribed in the ordinance providing for their issuance. This ordinance shall also declare that a statutory mortgage lien exists upon the property so to be purchased or constructed, fix minimum rates for water to be collected prior to the payment of all of the revenue bonds so issued, and shall pledge the revenue derived from the operation of the waterworks for the purpose of paying those bonds and the interest thereon. This pledge shall definitely fix and determine the amount of revenue which must be set apart and applied to the payment of the principal of and interest on the bonds and the proportion of the balance of the revenue which is to be set aside as a proper and adequate depreciation account. The remainder of the revenue shall be set aside for the reasonable and proper operation and maintenance of the waterworks. The rates to be charged for the services from the waterworks shall be sufficient to provide for the payment of interest upon all bonds and to create a sinking fund to pay the principal thereof as and when the bonds become due, to provide for the operation and maintenance of the system and to provide an adequate depreciation fund.
     With respect to instruments for the payment of money issued under this Section either before, on, or after the effective date of this amendatory Act of 1989, it is and always has been the intention of the General Assembly (i) that the Omnibus Bond Acts are and always have been supplementary grants of power to issue instruments in accordance with the Omnibus Bond Acts, regardless of any provision of this Act that may appear to be or to have been more restrictive than those Acts, (ii) that the provisions of this Section are not a limitation on the supplementary authority granted by the Omnibus Bond Acts, and (iii) that instruments issued under this Section within the supplementary authority granted by the Omnibus Bond Acts are not invalid because of any provision of this Act that may appear to be or to have been more restrictive than those Acts.
     The amendatory Acts of 1971, 1972 and 1973 are not a limit upon any municipality which is a home rule unit.