70 ILCS 605/3-7

At the hearing, the court shall determine whether or not the requisite number of owners owning the required acreage of land signed the petition or joined as petitioners. The affidavit of one or more credible persons may be taken as prima facie evidence of the sufficiency of the signing of the petition. Any owner of land situated within the proposed district may, at or prior to the time fixed for hearing, file objections to the sufficiency of the petition on the ground that it does not fulfill the requirements of Section 3-3, and, after filing such objections, may be heard with reference thereto and introduce evidence thereon.