70 ILCS 605/12-6
If the work of a district or a proposed district includes the construction of a levee to protect the lands within the district from overflow, or the erection and operation of a pumping plant, or both, then all lands so protected may be included within the district, either at the time of organization or by subsequent annexation. The fact that a portion of those lands are already within the boundaries of another district shall not prevent their inclusion in the district so constructing or proposing to construct the levee and pumping plant if the drainage system of such other district does not include a levee and pumping plant. If a ditch or covered drain leading from lands lying within one drainage district is connected, other than by the drainage system of that district, with a ditch or covered drain of another district and such lands are benefited by the ditch or covered drain of the other district, then the lands so connected and benefited may be included in or annexed to the other district and the fact of such connection shall be deemed to be a waiver of any objection to such inclusion or annexation upon the ground that such land is already within the boundaries of and subject to assessment by an organized drainage district.
70 ILCS 605/12-6