COLUMBUS, Ohio — Ohio environmental regulators have finalized updates to state drinking water rules that strengthen how community water systems monitor radioactive contaminants, tightening oversight without changing existing safety limits.
The Ohio Environmental Protection Agency announced that the director formally adopted amendments to three sections of the Ohio Administrative Code — inorganic chemical monitoring, organic chemical monitoring, and radionuclide monitoring — on Feb. 9, 2026. The changes will take effect Feb. 27, 2026.
The revisions to Rule 3745-81-26 clarify when and how often community public water systems must test for radionuclides, including uranium, radium-226, radium-228, gross alpha activity, and beta particle radiation. The rule standardizes monitoring schedules, detection limits, and compliance calculations statewide.
Under the finalized rule, new community water systems and systems that begin using a new water source must initiate radionuclide monitoring within the first quarter of operation. Existing systems are required to sample at locations representative of all active sources unless the Ohio EPA director determines an alternate location is more appropriate.
The rule also formalizes reduced monitoring schedules for systems with consistently low contaminant levels, allowing testing as infrequently as once every nine years. However, reduced monitoring is no longer fixed; any increase in results can trigger more frequent sampling, and exceedances of maximum contaminant levels require quarterly monitoring until compliance is restored.
In addition, the rule tightens how “non-detect” laboratory results are treated in compliance calculations and explicitly codifies detection limits for radionuclides such as radium, uranium, and tritium. The changes are intended to improve consistency across laboratories and prevent underestimating potential risks.
The final rule also expands the director’s authority to designate water systems as vulnerable to radioactive contamination based on nearby sources, including nuclear facilities. Systems deemed vulnerable may be required to conduct more frequent monitoring, with waivers explicitly prohibited under the rule.
The change is particularly significant for communities with a long history of radioactive contamination, such as Piketon in Pike County, home to the former Portsmouth Gaseous Diffusion Plant. In those areas, groundwater and surface water have been impacted by decades of uranium enrichment activity, making early detection and continuous monitoring necessary for protecting public drinking water supplies.
Under the updated rule, Ohio EPA may require more frequent testing for radioactive contaminants in water systems serving such communities, even if past results have remained below regulatory limits. Regulators say the provision is intended to ensure that systems located near legacy or active radioactive sites do not rely on infrequent testing that could delay detection of emerging contamination.
Ohio EPA officials said the amendments do not alter federal or state maximum contaminant levels for radionuclides but are designed to strengthen early detection, transparency, and regulatory oversight of drinking water quality.
Below is a copy of the now-approved draft proposal: