Contaminant · PFAS
PFBS in drinking water
Perfluorobutanesulfonic acid, a short-chain replacement for PFOS.
highest recorded single-sample basis; sampled 2023–2025. Source: EPA records; Calhoun (GA1290000).
What the rules say
PFBS has no individual limit. EPA's 2024 rule used a health-based water concentration of 2,000 ng/L for PFBS inside a mixture 'hazard index'; EPA proposed rescinding the hazard index in May 2026.
What EPA's assessment says
EPA's 2021 PFBS toxicity assessment cites thyroid, kidney and developmental effects in animal studies.
Across the country
EPA tested 10,307 water systems for PFBS and found it in 1,707. Half of the systems that found it measured less than 4.4 ppt, and one in ten measured more than 11.0 ppt.
EPA's final UCMR 5 occurrence file contains 66,355 PFBS results from 10,307 systems. 5,690 results were at or above the minimum reporting level, across 1,707 systems. Among detections, the median was 4.4 ppt and the 90th percentile was 11.0 ppt.
0 systems had a result at or above the reference on the page's stated comparison basis. For contaminants with a limit, that basis is the yearly average at the highest sampling location, not the highest single sample.
Systems with the highest recorded PFBS results
| System | State | Population served | Recorded value | Records / periods |
|---|---|---|---|---|
| Calhoun GA1290000 | Georgia | 53,090 | 290 ppt | 8 |
| Safford City of AZ0405005 | Arizona | 20,600 | 144 ppt | 12 |
| Chattooga County GA0550000 | Georgia | 9,190 | 150 ppt | 10 |
| Gadsden, the Wwsb of the City of AL0000577 | Alabama | 44,637 | 155 ppt | 4 |
| Globe City of AZ0404008 | Arizona | 7,536 | 113 ppt | 2 |
| Shelby County Commission-Water Services AL0001671 | Alabama | 40,101 | 114 ppt | 8 |
| Newton Falls City OH7802311 | Ohio | 6,109 | 220 ppt | 4 |
| Arizona Water Co - Pinal Valley AZ0411009 | Arizona | 134,432 | 91.1 ppt | 6 |
| Sterrett-Vandiver Water System, INC. AL0001164 | Alabama | 3,252 | 110 ppt | 4 |
| Highland Water Authority AL0000580 | Alabama | 3,963 | 134 ppt | 4 |
| Northeast Etowah County Water Co-Op AL0000587 | Alabama | 4,275 | 140 ppt | 4 |
| Chatsworth GA2130000 | Georgia | 28,262 | 81.0 ppt | 18 |
| Wetumpka, the Ww & Sb of the City of AL0000551 | Alabama | 10,137 | 82.0 ppt | 4 |
| Tri Community Water System AL0000549 | Alabama | 11,832 | 73.0 ppt | 8 |
| Clanton, the Ww & Sb of the City of AL0000213 | Alabama | 13,500 | 85.0 ppt | 4 |
| Holtville Water System AL0000540 | Alabama | 12,600 | 62.0 ppt | 4 |
| Millbrook Utilities AL0000539 | Alabama | 5,451 | 65.0 ppt | 5 |
| Marbury Water System, INC. AL0000013 | Alabama | 8,670 | 73.0 ppt | 4 |
| Alabaster Water Department, City of AL0001148 | Alabama | 40,986 | 85.0 ppt | 10 |
| Scua Upper Seven Mile 090400114 | Arizona | 8,478 | 53.8 ppt | 8 |
| Brookwood Comm Wtr System NC0326127 | North Carolina | 15,380 | 63.3 ppt | 29 |
| Payson Town of AZ0404032 | Arizona | 17,682 | 54.8 ppt | 33 |
| Talladega County Commission AL0001685 | Alabama | 4,749 | 47.7 ppt | 2 |
| Hesperia MI0003130 | Michigan | 954 | 49.0 ppt | 4 |
| Floyd County GA1150001 | Georgia | 46,143 | 93.3 ppt | 14 |
Filters and testing
NSF/ANSI 58 (reverse osmosis); carbon filters vary for short-chain PFAS
A standard number by itself is not a contaminant claim. Check the product's current certification listing and performance data sheet for PFBS or the specific contaminant you want to reduce. A utility-level record is not a test of your own faucet.