Question 1

What is Perfluorohexane Sulfonic Acid?

Accepted Answer

Perfluorohexane Sulfonic Acid (PFHxS) is a per- and polyfluoroalkyl substance (PFAS) – a synthetic chemical used in manufacturing, firefighting foam, and consumer products. It persists indefinitely in water and the human body.

Question 2

Is PFHxS in my drinking water?

Accepted Answer

EPA UCMR5 testing (2023-2025) monitors PFHxS at 6,800+ US water systems. Enter your ZIP code at KnowYourExposure.com to see if PFHxS has been detected in your specific utility.

Question 3

What is the EPA limit for PFHxS?

Accepted Answer

The EPA drinking water limit for PFHxS is 10 parts per trillion (ppt). Utilities have until 2029 to reduce levels below this threshold under the 2024 PFAS Rule.

Question 4

What are the health effects of PFHxS?

Accepted Answer

PFHxS exposure has been linked to: Thyroid disease, Neurodevelopmental effects, Immune suppression. Long-term exposure increases risks even at low doses.

Question 5

How do I remove PFHxS from my water?

Accepted Answer

Certified reverse osmosis systems remove 90%+ of most PFAS including PFHxS. Activated carbon and ion exchange filters also work. Boiling does NOT remove PFAS – it concentrates them.

Question 6

What is the CAS number for Perfluorohexane Sulfonic Acid?

Accepted Answer

The CAS Registry Number for Perfluorohexane Sulfonic Acid is 355-46-4.

PFHxS: Health Effects, EPA Limits & Sources (2026)