pfasUCMR5Unregulated by EPA

11Cl-PF3OUdS (11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid)

Reviewed for accuracy against EPA data and peer-reviewed literature · Updated May 2026

11Cl-PF3OUdS is a chlorinated ether PFAS compound included in EPA's UCMR5 monitoring list. It belongs to a class of chlorinated polyfluorinated ether sulfonates (Cl-PFESA) used as PFOS replacements primarily in China for the electroplating industry. Its detection in US water reflects the global movement of PFAS through trade and environmental transport.

CAS 763051-92-9

EPA legal limit

No federal limit

Maximum Contaminant Level

EWG health guideline

No guideline

Science-based, stricter target

Health effects

Toxicological data on 11Cl-PF3OUdS is limited but emerging research indicates thyroid disruption and liver effects in animal studies. Cl-PFESA compounds are structurally similar to PFOS and are expected to share some of its toxicological properties. Bioaccumulation data in humans is limited.

Where it comes from

Used in metal electroplating as a PFOS replacement, primarily in China. Detected globally in surface water, fish, and human blood. Its presence in US drinking water reflects both domestic electroplating sources and global transport of PFAS compounds via water and atmospheric deposition.

How it's regulated

No federal EPA MCL. Not regulated under the 2024 PFAS NPDWR. Monitored under UCMR5. No EWG health guideline established. Classified as an emerging PFAS contaminant of concern.

How to filter 11cl-pf3ouds

Not all filters address 11cl-pf3ouds. Look for independently certified filters—NSF International certification means the removal claim has been independently verified.

Reverse osmosis (RO)NSF 58
NSF 58 certified RO system

Frequently asked questions

What is 11cl-pf3ouds?

11Cl-PF3OUdS is a chlorinated ether PFAS compound included in EPA's UCMR5 monitoring list. It belongs to a class of chlorinated polyfluorinated ether sulfonates (Cl-PFESA) used as PFOS replacements primarily in China for the electroplating industry. Its detection in US water reflects the global movement of PFAS through trade and environmental transport.

What are the health effects of 11cl-pf3ouds?

Toxicological data on 11Cl-PF3OUdS is limited but emerging research indicates thyroid disruption and liver effects in animal studies. Cl-PFESA compounds are structurally similar to PFOS and are expected to share some of its toxicological properties. Bioaccumulation data in humans is limited.

Is 11cl-pf3ouds regulated in drinking water?

No federal EPA MCL. Not regulated under the 2024 PFAS NPDWR. Monitored under UCMR5. No EWG health guideline established. Classified as an emerging PFAS contaminant of concern.

Where does 11cl-pf3ouds come from?

Used in metal electroplating as a PFOS replacement, primarily in China. Detected globally in surface water, fish, and human blood. Its presence in US drinking water reflects both domestic electroplating sources and global transport of PFAS compounds via water and atmospheric deposition.

How do I remove 11cl-pf3ouds from tap water?

The most effective methods for removing 11cl-pf3ouds are: Reverse osmosis (RO), NSF 58 certified RO system. Look for NSF-certified systems—independent certification confirms removal claims have been verified.

Is 11cl-pf3ouds in your water?

Enter your ZIP code to see the measured level in your specific utility.