Nothing in this Act contained shall apply to or be construed in any manner to affect the property, real, personal or mixed and wherever situated, or the channels, drains, ditches and outlets and adjuncts and additions thereto and their use, operation and maintenance and the right to the flow of water therein for sewage dilution, or affect the jurisdiction, rights, powers, duties and obligations of any existing sanitary district or any sanitary district or any city or village which now has a population of one million or more within its territorial limits.
70 ILCS 2105/27