EPA Cracks Down on Perchlorate in Drinking Water
Published Date: 1/6/2026
Proposed Rule
Summary
The EPA is proposing new rules to limit perchlorate in drinking water to keep it safe and healthy for everyone. Water systems will need to test for perchlorate, fix problems if levels are too high, and share info with the public. These changes affect water providers nationwide, with public comments open until March 9, 2026, and could mean some costs but better health protection.
Analyzed Economic Effects
5 provisions identified: 2 benefits, 3 costs, 0 mixed.
New perchlorate limits proposed
The EPA proposes a health-based Maximum Contaminant Level Goal (MCLG) for perchlorate of 0.02 mg/L (20 micrograms per liter) and is seeking comment on enforceable Maximum Contaminant Levels (MCLs) of 0.02 mg/L (20 µg/L), 0.04 mg/L (40 µg/L), or 0.08 mg/L (80 µg/L). These standards would apply to public water systems and determine when systems must reduce perchlorate in drinking water.
New monitoring rules for water systems
The EPA would require community water systems (CWSs) and non-transient non-community water systems (NTNCWSs) to monitor drinking water for perchlorate, with monitoring frequency based on previous results and options to use previously collected data or reduced monitoring if initial samples are low. The proposal includes provisions to automatically reduce monitoring frequency for systems with low or non-detect results.
Required fixes when levels exceed MCL
If a public water system exceeds the perchlorate MCL, the system would need to mitigate the contamination by installing treatment (examples: ion exchange, reverse osmosis, biological treatment), switching to an uncontaminated source, or using certified point-of-use devices for small systems. Systems that exceed the MCL would also be required to report and take actions to come back into compliance.
EPA estimates nationwide costs exceed benefits
The EPA estimates annualized incremental nationwide costs and benefits (2023 dollars) for each MCL option: for a 20 µg/L MCL, annualized cost $16.1 million (3% discount) and monetized benefit $8.3 million (net -$7.8 million); for 40 µg/L, cost $11.2 million and benefit $6.8 million (net -$4.4 million); for 80 µg/L, cost $8.6 million and benefit $5.3 million (net -$3.3 million). The Agency concluded that monetized benefits do not justify the costs for any of the proposed MCLs.
Public notice and consumer reporting rules
Water systems would have to provide Consumer Confidence Reports and Tier 1 public notifications to customers when perchlorate levels exceed the MCL, with Tier 1 notification required for an exceedance because of the effect on the most sensitive population identified. These notices would inform customers about perchlorate detections and any required actions.
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Key Dates
Department and Agencies
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