This bill, titled the Primacy Certainty Act of 2025 , amends the Safe Drinking Water Act to establish explicit timelines for the Environmental Protection Agency's (EPA) decisions regarding State applications for primary enforcement responsibility over underground injection control (UIC) programs, particularly for Class VI wells . It aims to provide certainty and expedite the process for States seeking to regulate these wells, which are primarily used for carbon sequestration. The legislation introduces a critical deadline: if the Administrator does not approve, disapprove, or partially approve a State's Class VI well UIC program application within 180 days , the Administrator must provide a detailed written explanation to the State. This explanation must include the status of the review, reasons for the delay, and an itemized list of specific deficiencies to be addressed. Crucially, if the Administrator fails to make a decision within 30 days following the 180-day period (totaling 210 days from submission), the State's complete application for Class VI wells will be considered automatically approved. This automatic approval applies if the State already has primary enforcement authority for one or more other classes of UIC wells, demonstrating existing regulatory capacity. To facilitate this process, the bill requires the Administrator to determine the completeness of a State's application within 10 days of submission. If this determination is not made within 10 days, the application is considered administratively complete upon the State's request. Furthermore, the bill specifies that any denial or partial disapproval must be based solely on the State not meeting the established criteria, and approval cannot be conditioned on provisions not explicitly required by the Act or included in the original application. The Act also mandates that the EPA work expeditiously with States on pre-application activities for Class VI wells and designate a single individual to coordinate the entire application process for each State. Finally, it requires the Administrator to submit a report to Congress within 90 days, detailing the availability of staff and resources needed to promptly implement these new requirements and identifying any necessary funding.