pfasUCMR5Unregulated by EPA

PFTrDA (perfluorotridecanoic acid)

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

PFTrDA is a thirteen-carbon long-chain carboxylic acid PFAS. It is among the longest-chain PFAS monitored under UCMR5 and is of elevated concern due to its extreme bioaccumulation potential. Detected at lower frequency than shorter-chain PFAS but present in multiple states.

CAS 72629-94-8

EPA legal limit

No federal limit

Maximum Contaminant Level

EWG health guideline

0.5 ppt

Science-based, stricter target

Health effects

PFTrDA has exceptional persistence in the body due to its thirteen-carbon chain. Animal studies show effects on liver, immune system, and reproduction. Its bioaccumulation profile is expected to be more pronounced than PFOA or PFDA. Very limited human exposure data exists at drinking water concentrations.

Where it comes from

Industrial use as a surfactant and processing aid in fluoropolymer manufacturing. Found in industrial wastewater and contaminated groundwater near PFAS manufacturing facilities. Rare in drinking water but detected in UCMR5 monitoring.

How it's regulated

No federal EPA MCL. Not individually regulated under the 2024 PFAS NPDWR. Monitored under UCMR5. EWG health guideline: 0.5 ppt, based on bioaccumulation potential analogous to other ultra-long-chain PFAS.

How to filter pftrda

Not all filters address pftrda. 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 pftrda?

PFTrDA is a thirteen-carbon long-chain carboxylic acid PFAS. It is among the longest-chain PFAS monitored under UCMR5 and is of elevated concern due to its extreme bioaccumulation potential. Detected at lower frequency than shorter-chain PFAS but present in multiple states.

What are the health effects of pftrda?

PFTrDA has exceptional persistence in the body due to its thirteen-carbon chain. Animal studies show effects on liver, immune system, and reproduction. Its bioaccumulation profile is expected to be more pronounced than PFOA or PFDA. Very limited human exposure data exists at drinking water concentrations.

Is pftrda regulated in drinking water?

No federal EPA MCL. Not individually regulated under the 2024 PFAS NPDWR. Monitored under UCMR5. EWG health guideline: 0.5 ppt, based on bioaccumulation potential analogous to other ultra-long-chain PFAS.

Where does pftrda come from?

Industrial use as a surfactant and processing aid in fluoropolymer manufacturing. Found in industrial wastewater and contaminated groundwater near PFAS manufacturing facilities. Rare in drinking water but detected in UCMR5 monitoring.

How do I remove pftrda from tap water?

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

Is pftrda in your water?

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