Creates the Data Center Water Transparency and Aquifer Protection Act. Provides that, beginning January 1, 2027, no data center operating within the State shall use water from the Mahomet Aquifer. Prohibits State agencies from issuing or renewing a permit authorizing a data center to withdraw groundwater from the Mahomet Aquifer. Requires existing data centers to transition to alternative water sources and cease all groundwater withdrawals from the Mahomet Aquifer by no later than January 1, 2028. Provides that a unit of local government may not enter into, enforce, or renew any nondisclosure agreement, confidentiality clause, or similar contractual provision with a data center that restricts the disclosure of information related to the data center's water use. Contains provisions concerning data confidentiality and public access. Establishes penalties for violations. Grants the Illinois Environmental Protection Agency rulemaking powers.