EPA Proposes First-Ever National Perchlorate Drinking Water Standard
EPA Proposes First-Ever National Perchlorate Drinking Water Standard
What Happened
The U.S. Environmental Protection Agency has proposed the first-ever national drinking water regulation for perchlorate, a chemical contaminant found in rocket fuel, fireworks, explosives, and certain fertilizers. The EPA is seeking public comment on three potential Maximum Contaminant Levels (MCLs): 20, 40, or 80 micrograms per liter.
A virtual public hearing is scheduled for February 19, 2026, with the comment period closing on March 9, 2026.
What Is Perchlorate?
Perchlorate is both a naturally occurring and man-made chemical compound. Its primary industrial uses include:
- Ammonium perchlorate: Solid rocket propellant (the primary use, accounting for the majority of manufactured perchlorate)
- Potassium perchlorate: Fireworks, flares, and pyrotechnics
- Sodium perchlorate: Analytical chemistry and certain industrial processes
- Perchloric acid: Laboratory reagent and electronics manufacturing
Perchlorate contamination in drinking water has been detected near military installations, defense contractors, and industrial sites where these compounds were manufactured, stored, or disposed of.
Health Effects
Perchlorate interferes with iodine uptake in the thyroid gland. This is a particular concern for:
- Pregnant women: Thyroid disruption during pregnancy can affect fetal brain development
- Infants and young children: Developing thyroid function is more vulnerable to disruption
- Individuals with iodine deficiency: Lower iodine intake increases susceptibility to perchlorate's effects
- People with existing thyroid conditions: Pre-existing thyroid disorders can be worsened
The EPA has set the health-based Maximum Contaminant Level Goal (MCLG) at 0.02 mg/L (20 micrograms per liter), representing the level with no expected health risk.
The Three Proposed MCL Options
| Option | MCL | Implications |
|---|---|---|
| Option A | 20 μg/L | Matches the MCLG. Maximum public health protection. Highest treatment costs for water systems. |
| Option B | 40 μg/L | Moderate standard. Balances health protection with treatment feasibility. |
| Option C | 80 μg/L | Least restrictive. Fewer water systems would need treatment upgrades. |
How Water Systems Remove Perchlorate
Public water systems that exceed the final MCL will need to install treatment technologies. The most effective methods for perchlorate removal include:
- Ion exchange: The most common and cost-effective method. Perchlorate-selective resins capture perchlorate ions from water. Regeneration produces a concentrated waste stream that must be managed.
- Biological reduction: Microorganisms convert perchlorate to chloride and oxygen under anaerobic conditions. Effective but requires careful process control.
- Activated carbon adsorption: Granular activated carbon can remove perchlorate, though it's generally less efficient than ion exchange for this specific contaminant.
- Reverse osmosis / nanofiltration: Membrane-based treatment can achieve high removal rates but at higher cost and with significant water waste.
Regardless of the final MCL chosen, water systems will also be required to monitor perchlorate levels and include results in their annual Consumer Confidence Reports.
Regulatory Background
This proposed rule has a complicated history. The EPA initially determined in 2020 that perchlorate regulation wasn't warranted. However, a D.C. Circuit Court decision subsequently mandated that the agency pursue regulatory action under the Safe Drinking Water Act. The current proposal is the result of that court order.
Despite the legal mandate, the EPA's own assessment notes that perchlorate generally "does not occur in public water systems at levels of public health concern" — a statement that will likely factor into public comment and potential legal challenges to whichever MCL is ultimately adopted.
What to Watch
- February 19, 2026: Virtual public hearing — stakeholders can provide testimony
- March 9, 2026: Public comment period closes
- Final rule: Expected later in 2026 or early 2027 — the final MCL may differ from the proposed options
- Compliance timeline: Water systems will likely have 3–5 years to comply after the final rule is published
Alliance's Take
Water treatment is one of Alliance Chemical's core markets, and new drinking water standards directly affect the chemicals our customers need. If the EPA adopts a perchlorate MCL — especially the more protective 20 μg/L option — water treatment facilities across the country will need to install or upgrade treatment systems.
For facilities evaluating their treatment options, Alliance Chemical supplies a range of water treatment chemicals including activated carbon, treatment reagents, and pH adjustment chemicals that support perchlorate removal processes. Ion exchange systems, in particular, require periodic chemical regeneration and waste stream management where reliable chemical supply matters.
If you operate a public water system and want to understand how this proposed rule might affect your chemical needs, our team is available at sales@alliancechemical.com to discuss product specifications and treatment chemical options.
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