Following a court order, the U.S. Environmental Protection Agency (EPA) is taking involuntary action to tighten regulations governing the presence of perchlorate in drinking water. This decision culminates a nearly two-decade-long rule development history, which has yielded perchlorate research, regulatory determinations, lawsuits, studies, guidance documentation, and best practices for public water systems.
What is Perchlorate?
Perchlorate is a chemical that is both naturally occurring and man-made. It's often used in rocket fuel, fireworks, matches, flares, and other products. Because it is highly soluble in water, the chemical can be found in drinking water sources. Exposure to perchlorate in drinking water and food interferes with iodine uptake by the thyroid gland, which can lead to hypothyroidism, adverse reproductive and developmental outcomes, and impacts on the cardiovascular system and brain development in infants.
What is EPA Proposing?
EPA proposed a National Primary Drinking Water Regulation (NPDWR) and a Maximum Contaminant Level Goal (MCLG) under the Safe Drinking Water Act for perchlorate.
EPA doesn’t currently have a Maximum Contaminant Level (MCL) set for perchlorate. The agency proposed to set the perchlorate MCLG at 0.02 milligrams per liter (mg/L). It is also proposing an enforceable MCL at 0.02 mg/L, 0.04 mg/L, or 0.08 mg/L, depending on public feedback.
In addition, EPA aims to set water system requirements for the following:
Who Could Be Affected?
EPA’s proposed changes could affect the following entities and others:
Community water systems
Non-transient, non-community water systems
Agencies responsible for developing, ensuring compliance with, and enforcing NPDWRs
What’s Next?
EPA will hold a virtual public hearing on these proposals on February 19, 2026. The agency is currently accepting public comments on these proposals through March 9, 2026. We will follow the draft rule developments and keep you informed.
