# 2026-00021: EPA Cracks Down on Perchlorate in Drinking Water 2026-00021, National Primary Drinking Water Regulation for Perchlorate, is a Federal Register proposed rule from Environmental Protection Agency published 2026-01-06, effective 2026-03-09; deemed significant under Executive Order 12866 (as of 2026-06-11). - Canonical: https://policyrisk.com/federal-register/2026-00021 - As of: 2026-06-11 - Plain-text twin of the page above; the HTML and this file carry the same facts. ## Facts - Document number: 2026-00021 - Title: National Primary Drinking Water Regulation for Perchlorate - Type: Proposed Rule - Agencies: Environmental Protection Agency - Citation: 91 FR 398 - Published: 2026-01-06 - Effective: 2026-03-09 - Comments close: not stated - Significant: yes (FR_METADATA) - Touches household money: no - Regulation identifier numbers: 2040-AG36 - Last updated: 2026-06-11 ## In one line EPA Cracks Down on Perchlorate in Drinking Water ## 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. ## Abstract The U.S. Environmental Protection Agency ("EPA" or the "Agency") is proposing a National Primary Drinking Water Regulation (NPDWR) for perchlorate and a health-based Maximum Contaminant Level Goal (MCLG) under the Safe Drinking Water Act (SDWA). In this action, the EPA is proposing to set the perchlorate MCLG at 0.02 mg/L (20 [micro]g/L). The EPA is also proposing and taking comment on setting an enforceable Maximum Contaminant Level (MCL) for perchlorate at 0.02 mg/ L (20 [micro]g/L), 0.04 mg/L (40 [micro]g/L), or 0.08 mg/L (80 [micro]g/L). The EPA is also proposing requirements for water systems to conduct monitoring for perchlorate in drinking water, take mitigation actions if the level exceeds the MCL, provide information about perchlorate to their consumers through public notification and consumer confidence reports, and report to their respective primacy agency. The Administrator has determined that the benefits of this regulation would not justify the costs; however, the EPA is required to issue an NPDWR and MCLG for perchlorate in response to the D.C. Circuit's decision in NRDC v. Regan. ## Effects PRIA read - New perchlorate limits proposed: benefit, medium. 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 pu… - New monitoring rules for water systems: cost, medium. 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.… - Required fixes when levels exceed MCL: cost, medium. 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. System… - Public notice and consumer reporting rules: benefit, low. 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 cust… - EPA estimates nationwide costs exceed benefits: cost, medium. 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 milli… ## Related documents - [2026-19071](https://policyrisk.com/federal-register/2026-19071): Partial Repeal of the Carbon Pollution Standards for Fossil Fuel-Fired Electric Generating Units, 2026-09-17 - [2026-19072](https://policyrisk.com/federal-register/2026-19072): Rescission of the Greenhouse Gas Findings for Fossil Fuel-Fired Power Plants and Repeal of Regulations for Power Plant Greenhouse Gas Emiss…, 2026-09-17 - [2026-18317](https://policyrisk.com/federal-register/2026-18317): Updated Definition of “Waters of the United States”, 2026-09-09 - [2026-14112](https://policyrisk.com/federal-register/2026-14112): Amendments and Nonconformance Penalties for Model Year 2027 and Later Heavy-Duty Highway Engines and Amendments to Inducement Provisions fo…, 2026-07-14 - [2026-13667](https://policyrisk.com/federal-register/2026-13667): Minor New Source Review Program Air Permitting Public Participation Requirements for State Implementation Plans, 2026-07-07 - [2026-13263](https://policyrisk.com/federal-register/2026-13263): Revisions To Establish the Sixth Unregulated Contaminant Monitoring Rule (UCMR 6) for Public Water Systems, 2026-07-01 ## Sources - [2026-00021 on federalregister.gov](https://www.federalregister.gov/documents/2026/01/06/2026-00021/national-primary-drinking-water-regulation-for-perchlorate) - [2026-00021 as published (PDF)](https://www.govinfo.gov/content/pkg/FR-2026-01-06/pdf/2026-00021.pdf) ## Related - [Previous: 2025-24272, Restoring Flexibility in the Child Care and Development Fund (CCDF)](https://policyrisk.com/federal-register/2025-24272) - [Next: 2026-00048, Safety Zone; West of Cyril E. King Airport, St. Thomas, VI](https://policyrisk.com/federal-register/2026-00048) - [All Federal Register documents](https://policyrisk.com/federal-register) Source: PRIA, https://policyrisk.com/federal-register/2026-00021 (as of 2026-06-11).