Methods Update Rules
The EPA periodically updates the list of approved methods to reflect advances in technology, refine quality assurance and quality control requirements, and provide entities more choices of approved compliance monitoring methods.
On this page:
Current Action
Proposed Methods Update Rule 22
The EPA signed a new proposed Methods Update Rule (MUR), MUR 22, on December 6, 2024. This action proposes to promulgate three new EPA methods into 40 CFR Part 136:
- EPA Method 1633A: an analytical method capable of measuring 40 PFAS compounds. This method was the result of a collaboration between the EPA and the Department of Defense.
- EPA Method 1621: an analytical method capable of measuring adsorbable organic fluorine.
- EPA Method 1628: an analytical method capable of measuring all 209 PCB congeners.
This action also proposes to codify analytical methods developed by Voluntary Consensus Standard Bodies (VCSB) as is consistent with the National Technology Transfer Act. These analytical methods include:
- ASTM D8421 measuring the same 40 PFAS compounds as EPA Method 1633A.
- Standard Method 4500-PAA measuring peracetic acid.
- Standard Method 4500-H2O2 measuring hydrogen peroxide.
This action also proposes to withdraw the existing EPA methods for measuring seven Aroclors (PCB mixtures). Finally, the EPA is proposing to simplify the sampling requirements for two volatile organic compounds, acrolein and acrylonitrile, and make a series of minor corrections to existing tables of approved methods.
Documents
The EPA accepted public comments on the proposed rule through March 24, 2025. The submitted comments and all supporting material for the proposed rule are available at regulations.gov. The Docket Number is EPA-HQ-OW-2024-0328.
- Proposed MUR 22 - Federal Register Notice (January 21, 2025)
- Fact Sheet - Proposed Rule: Methods Update Rule 22 (pdf)
Recent Action
Routine Methods Update Rule 2
The EPA promulgated a final routine MUR, rMUR 2, on April 16, 2024. In rMUR 2, the EPA approved:
- Revised EPA bacteria methods.
- New or revised methods published by voluntary consensus standard bodies, such as ASTM International and the Standard Methods Committee.
- Methods reviewed under the Alternate Test Procedures (ATP) program.
Documents
All supporting materials for rMUR 2 can be found on the EPA’s docket at regulations.gov. The Docket Number is EPA-HQ-OW-2022-0901.
- Final rMUR 2 Federal Register Notice (April 16, 2024).
- Fact Sheet; Final Rule: Clean Water Act Methods Update Rule for the Analysis of Effluent (pdf) .
Background Information
Additional Information
For further information on MURs generally, please contact Tracy Bone (bone.tracy@epa.gov) or 202-564-5257.