As anticipated, the Environmental Protection Agency (EPA) announced on June 18, 2020, that it will not regulate perchlorate, a substance primarily found in rocket fuel and munitions, under the Safe Drinking Water Act (SDWA). Before determining to regulate a chemical or substance under the SDWA, the EPA must consider whether (1) the contaminant may have an adverse effect on the health of persons; (2) the contaminant is known to occur or there is a substantial likelihood that the contaminant will occur in public water systems with a frequency and at levels of public health concern; and (3) in the sole judgment of the Administrator, regulation of such contaminant presents a meaningful opportunity for health risk reduction for persons served by public water systems. 42 U.S.C. § 300g-1(b)(1)(A). In its announcement, the EPA concludes that perchlorate does not meet these criteria for regulation.

In 2011, the EPA formally published its determination to regulate perchlorate under the SDWA and initiated the process for developing a Maximum Contaminant Level Goal (MCLG) and National Primary Drinking Water Regulation (NPDWR) to regulate perchlorate in drinking water. In 2019, the Agency issued a proposal to set a MCLG for perchlorate at 56 parts per billion—a level that would be more than ten times higher than most existing state regulatory levels. In addition to its proposal, the EPA solicited comments on three alternative proposals, including whether the EPA should withdraw the Agency’s 2011 determination and forgo regulation of the substance.

After nearly 1,500 comments were submitted in response to the EPA’s proposal, the Agency has now announced that it is formally withdrawing its 2011 determination and will not seek to implement regulatory standards for perchlorate under the SDWA. In making the decision not to regulate perchlorate, the EPA determined that it does not occur “with a frequency and at levels of public health concern” as defined within the SDWA. According to the EPA, “even at the most stringent regulatory levels considered in the 2019 proposal (18 g/µL), not more than 15 systems (0.03% of all water systems in the U.S. serving approximately 620,000 people) would need to take action to reduce levels of perchlorate.”

The EPA’s recent decision may not be the final time that the Agency is required to consider potential regulation of perchlorate, as environmental groups are likely to challenge the EPA’s decision in the coming months. We will provide updates as this issue continues to develop.