Contaminant · PFAS
PFDA in drinking water
Perfluorodecanoic acid, a long-chain PFAS.
What the rules say
PFDA has no federal limit; EPA finalized an IRIS toxicity assessment in 2024 but no drinking water reference concentration.
What EPA's assessment says
EPA's 2024 IRIS assessment for PFDA cites developmental, liver and immune effects.
Across the country
EPA tested 10,307 water systems for PFDA and found it in 17. Half of the systems that found it measured less than 3.5 ppt, and one in ten measured more than 5.6 ppt.
EPA's final UCMR 5 occurrence file contains 66,360 PFDA results from 10,307 systems. 31 results were at or above the minimum reporting level, across 17 systems. Among detections, the median was 3.5 ppt and the 90th percentile was 5.6 ppt.
Systems with the highest recorded PFDA results
| System | State | Population served | Recorded value | Records / periods |
|---|---|---|---|---|
| Pico Rivera - City, Water Dept. CA1910042 | California | 40,600 | 5.6 ppt | 4 |
| Emmaus Borough Public Water PA3390032 | Pennsylvania | 14,000 | 7.0 ppt | 2 |
| Payson Town of AZ0404032 | Arizona | 17,682 | 3.5 ppt | 5 |
| Nisky Center VI1000037 | U.S. Virgin Islands | 550 | 3.6 ppt | 2 |
| Jayuya Urbano PR0002712 | Puerto Rico | 7,746 | 12.4 ppt | 1 |
| City of Clovis CA1010003 | California | 130,130 | 3.1 ppt | 2 |
| Patillas Urbano PR0004835 | Puerto Rico | 32,222 | 5.5 ppt | 1 |
| Lake Arrowhead CSD CA3610005 | California | 7,038 | 3.9 ppt | 3 |
| Pico WD CA1910125 | California | 22,051 | 5.1 ppt | 1 |
| Veolia Water Delaware, INC DE0000564 | Delaware | 100,495 | 4.7 ppt | 3 |
| Pequenakonck Elementary School NY5907717 | New York | 700 | 3.8 ppt | 1 |
| Metropolitano PR0002591 | Puerto Rico | 1,084,637 | 7.5 ppt | 1 |
| South Montebello Irrigation Dist. CA1910153 | California | 15,021 | 3.7 ppt | 1 |
| Wartrace Water System TN0000730 | Tennessee | 3,576 | 3.4 ppt | 1 |
| Manchester Water Department TN0000429 | Tennessee | 24,975 | 3.0 ppt | 1 |
| Lafayette GA2950002 | Georgia | 18,177 | 3.0 ppt | 1 |
| Bealeton Regional VA6061129 | Virginia | 4,250 | 3.0 ppt | 1 |
Filters and testing
NSF/ANSI 53 or 58 with a PFAS reduction claim
A standard number by itself is not a contaminant claim. Check the product's current certification listing and performance data sheet for PFDA or the specific contaminant you want to reduce. A utility-level record is not a test of your own faucet.