Maryland PFAS results from EPA's final data
Report published Nov 14, 2026 · EPA UCMR 5 final data file of Oct 15, 2026 (samples collected 2023–2025) · Method · National results →
13 Maryland water systems serving 162,211 people had PFAS above a 2024 federal limit in EPA's final round of nationwide PFAS testing: 17% of the 76 Maryland systems tested, compared with 11% nationally.
Highest PFOA or PFOS averages in Maryland
- Town of Thurmont Thurmont · PFOS44.5 ppt
- Town of Elkton Elkton · PFOA22.6 ppt
- City of Westminster Westminster · PFOA11.4 ppt
- City of Taneytown Taneytown · PFOS10.4 ppt
- City of Salisbury Salisbury · PFOS10 ppt
- Town of Hampstead Hampstead · PFOA9.05 ppt
- Town of Mount Airy Mount Airy · PFOA8.45 ppt
- City of Aberdeen Aberdeen · PFOS8.15 ppt
- Maryland American Water Bel Air South · PFOA7.6 ppt
- Town of Middletown Middletown · PFOS6.4 ppt
- Town of Poolesville Poolesville · PFOS6.05 ppt
- Boonsboro – Keedysville Water System Boonsboro · PFOA5.9 ppt
- Town of Manchester Manchester · PFOA4.4 ppt
- City of Fruitland Fruitland · PFOS2.05 ppt
Chart data as a table
| System | ppt |
|---|---|
| Town of Thurmont · Thurmont · PFOS | 44.5 |
| Town of Elkton · Elkton · PFOA | 22.6 |
| City of Westminster · Westminster · PFOA | 11.4 |
| City of Taneytown · Taneytown · PFOS | 10.4 |
| City of Salisbury · Salisbury · PFOS | 10 |
| Town of Hampstead · Hampstead · PFOA | 9.05 |
| Town of Mount Airy · Mount Airy · PFOA | 8.45 |
| City of Aberdeen · Aberdeen · PFOS | 8.15 |
| Maryland American Water · Bel Air South · PFOA | 7.6 |
| Town of Middletown · Middletown · PFOS | 6.4 |
| Town of Poolesville · Poolesville · PFOS | 6.05 |
| Boonsboro – Keedysville Water System · Boonsboro · PFOA | 5.9 |
| Town of Manchester · Manchester · PFOA | 4.4 |
| City of Fruitland · Fruitland · PFOS | 2.05 |
Largest systems above a limit
| # | System | People served |
|---|---|---|
| 1 | City of Westminster Westminster Above: PFOA, PFOS | 35,256 |
| 2 | City of Salisbury Salisbury Above: PFOS | 30,343 |
| 3 | City of Aberdeen Aberdeen Above: PFOA, PFOS | 18,006 |
| 4 | Town of Elkton Elkton Above: PFOA, PFOS | 15,625 |
| 5 | Maryland American Water Bel Air South Above: PFOA, PFOS | 13,200 |
| 6 | Town of Mount Airy Mount Airy Above: PFOA, PFOS | 9,890 |
| 7 | City of Taneytown Taneytown Above: PFOA, PFOS | 6,750 |
| 8 | Town of Hampstead Hampstead Above: PFOA, PFOS | 6,600 |
| 9 | Town of Thurmont Thurmont Above: PFOA, PFOS | 6,200 |
| 10 | Town of Poolesville Poolesville Above: PFOA, PFOS | 6,005 |
All 13 Maryland systems above a limit
Every Maryland community water system whose UCMR 5 results averaged above a 2024 federal PFAS limit, largest first. Systems that were not tested are not listed: not tested is not the same as not detected.
Full list: 13 systems, largest first
| System | People served |
|---|---|
| City of Westminster Westminster Above: PFOA, PFOS | 35,256 |
| City of Salisbury Salisbury Above: PFOS | 30,343 |
| City of Aberdeen Aberdeen Above: PFOA, PFOS | 18,006 |
| Town of Elkton Elkton Above: PFOA, PFOS | 15,625 |
| Maryland American Water Bel Air South Above: PFOA, PFOS | 13,200 |
| Town of Mount Airy Mount Airy Above: PFOA, PFOS | 9,890 |
| City of Taneytown Taneytown Above: PFOA, PFOS | 6,750 |
| Town of Hampstead Hampstead Above: PFOA, PFOS | 6,600 |
| Town of Thurmont Thurmont Above: PFOA, PFOS | 6,200 |
| Town of Poolesville Poolesville Above: PFOA, PFOS | 6,005 |
| Town of Middletown Middletown Above: PFOA, PFOS | 5,132 |
| Town of Manchester Manchester Above: PFOA | 4,954 |
| Boonsboro – Keedysville Water System Boonsboro Above: PFOA | 4,250 |
The same list, with PFOA and PFOS averages, is in the data download.
Which limits were exceeded
| PFAS | Federal limit | Systems above it |
|---|---|---|
| PFOA 131,868 people | 4 ppt | 12 |
| PFOS 153,007 people | 4 ppt | 11 |
| PFHxS | 10 ppt | 0 |
| PFNA | 10 ppt | 0 |
| GenX (HFPO-DA) | 10 ppt | 0 |
| Hazard Index | 1 | 0 |
"–" in the table above means not detected. A system can be above more than one limit. EPA proposed in May 2026 to rescind the PFHxS, PFNA, GenX and Hazard Index limits. That proposal is not final.
Data and how to cite it
- Download every Maryland water system as CSV (PFOA and PFOS averages, systems above a limit, lead, violations).
- EPA's source file: UCMR 5 occurrence data.
Suggested citation:
Tap Water Results, "Maryland PFAS results from EPA's final UCMR 5 data" (published Nov 14, 2026, EPA data file of Oct 15, 2026). https://tapwaterresults.com/pfas/maryland/
You're welcome to quote and republish these figures with a link back. Questions from reporters: see contact.
Method
For each system we average each entry point's UCMR 5 results (non-detects count as zero, complete sets of samples only) and compare the highest entry-point average with the 2024 federal limit, using EPA's rounding. This is how EPA compares UCMR 5 results to the limits in its own data summary, and our national counts match EPA's published table within 2% (how we check). Results are monitoring data from 2023–2025, not compliance determinations, and treatment installed since then is not reflected. Full method.
Questions
How many Maryland water systems have PFAS above the limit?
13 of the 76 Maryland community water systems EPA tested in 2023–2025 (17%) had at least one entry-point average above a 2024 federal PFAS limit. They serve 162,211 people. Nationally the share is 11%.
Are these systems violating the law?
Not yet. Systems have until 2029 to meet the 2024 limits, and EPA has proposed moving the PFOA and PFOS deadline to 2031 and rescinding the other limits. EPA's UCMR 5 results are monitoring data and do not determine compliance.
Which systems were tested?
EPA's UCMR 5 tested every community water system serving more than 3,300 people and a representative sample of smaller ones. Systems that were not tested have no federal result, which is not the same as having no PFAS.
All Maryland water systems → · National results → · PFAS results for every state →
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.