11Cl-PF3OUdS
11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid
- EPA federal limit
- No federal limit
- Detected in
- 10,289 systems
- Regulatory status
- Unregulated (UCMR 5)
What is 11Cl-PF3OUdS?
11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid, known as 11Cl-PF3OUdS, is a man-made chemical that belongs to the PFAS family — a group of thousands of synthetic chemicals often called "forever chemicals" because they break down very slowly in the environment and in the human body. It is classified as a long-chain chlorinated ether PFAS, meaning it has a specific chemical structure that makes it especially resistant to breaking down. Like other PFAS compounds, 11Cl-PF3OUdS can build up over time in water, soil, and living things.
Where does it come from?
11Cl-PF3OUdS is released primarily through industrial processes and has been found in some consumer products. Likely sources include the manufacturing of stain-resistant fabrics, water-repellent coatings, and certain industrial chemicals. It may also be present near industrial facilities that produce or use fluorinated compounds.
Health concerns
Research on 11Cl-PF3OUdS is still in early stages, and published data on its health effects are limited. Some animal studies have associated similar long-chain PFAS compounds with liver stress, immune system changes, and hormonal disruption, but these findings have not been fully confirmed in humans. Because direct human data on this specific compound is scarce, scientists cannot yet draw firm conclusions. If you have personal health concerns, consult a healthcare provider.
EPA standard
The EPA has not established a Maximum Contaminant Level (MCL) — a legal limit for how much of a chemical is allowed in public drinking water — for 11Cl-PF3OUdS. This means water utilities are not currently required to test for or remove it. Without a federal limit, there is no guaranteed safety threshold protecting the public from this compound.
What you can do
If you are concerned about 11Cl-PUdS in your water, consider using a certified reverse osmosis filter or a granular activated carbon filter, both of which research studies indicate can reduce PFAS levels in drinking water. Ion exchange filters are another effective option. Never rely on boiling your water — boiling does not remove PFAS and can actually concentrate them.
About this summary: Narrative text on this page was drafted by an AI model (claude-sonnet-4-6) from EPA UCMR 5 data and reviewed before publication. The numeric data above is reported by water utilities directly to the EPA. If you spot an error, email data@checkyourwater.org.