Question 1

What is Perfluorobutane Sulfonic Acid?

Accepted Answer

Perfluorobutane Sulfonic Acid (PFBS) 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 PFBS in my drinking water?

Accepted Answer

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

Question 3

What is the EPA limit for PFBS?

Accepted Answer

The EPA drinking water limit for PFBS is 2000 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 PFBS?

Accepted Answer

PFBS exposure has been linked to: Thyroid disease, Developmental neurotoxicity, Kidney effects. Long-term exposure increases risks even at low doses.

Question 5

How do I remove PFBS from my water?

Accepted Answer

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

Question 6

What is the CAS number for Perfluorobutane Sulfonic Acid?

Accepted Answer

The CAS Registry Number for Perfluorobutane Sulfonic Acid is 375-73-5.

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