EPA’s 24.5 ppb reference dose (the maximum dose without any risk, abbreviated RfD) may be used by officials across the U.S. to make site-specific cleanup or interim drinking water standard decisions involving perchlorate. States and private parties also may look to EPA’s RfD and Drinking Water Equivalent Level (DWEL) to make similar decisions.
In July 2020, under the first Trump Administration, U.S. EPA made a determination under the Safe Drinking Water Act that that perchlorate did not merit additional federal regulation. That determination was subsequently upheld in 2022 under the Biden Administration .
However in 2023, litigation that focused on EPA’s administrative requirement to set a standard (rather than the actual science or health implications of perchlorate itself resulted in a ruling that compels EPA to issue a “proposed” National Primary Drinking Water Regulation for perchlorate by November 21, 2025, and a final regulation by May 21, 2027.
This begins a public process with opportunities for stakeholder input, EPA may request extensions to these deadlines, however as of June 2025 the agency has reported it is on track to meet them.