Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

This is not the current EPA website. To navigate to the current EPA website, please go to www.epa.gov. This website is historical material reflecting the EPA website as it existed on January 19, 2025. This website is no longer updated and links to external websites and some internal pages may not work. More information »

JavaScript appears to be disabled on this computer. Please click here to see any active alerts.

Clean Water Act Analytical Methods

Methods Update Rule 22
- Proposed Rule
Methods 1621 and 1633A for AOF and PFAS
- Methods 1621 and 1633A

The EPA publishes laboratory analytical methods (test procedures) that are used by industries and municipalities to analyze the chemical, physical and biological components of wastewater and other environmental samples required by the Clean Water Act.

Current and Recent Actions

Approved CWA Methods

Other CWA Methods

Optional methods for analyzing wastewater and biosolids (not approved under 40 CFR Part 136):

Chemical
Microbiological
including MST Methods 1696 & 1697
Biosolids

Alternate Test Procedures

Development of modified EPA methods or new methods

Regulations and Support Documents

Regulatory History for:
- Methods Update Rules
- Microbiological methods
- Oil & grease
- Cyanide
- Dioxins & furans
- Mercury and chromium-VI
Other methods support documents
Toxic and Priority Pollutant lists
Legal authority for methods