- PWSID
- PA1150108
- State
- Pennsylvania
- System type
- community water system (CWS)
- Population served
- 6,328
- City
- Kennett Square
- Counties
- Chester County
- Primary source water
- surface water (purchased)
- UCMR 5 sampling
- 2023-01-18 to 2024-01-29 · 3 entry point(s) · water types: SW
- Service-area boundary
- authoritative
PFOA ≥ 3 × its limit highest single result
PFOA 1–3 × its limit worst entry-point average
Open on the Pennsylvania map · All Pennsylvania systems · All results
These are monitoring results collected under EPA's Fifth Unregulated Contaminant Monitoring Rule (UCMR 5) at entry points, where treated water enters the distribution system; they are not tap-water samples. They are not compliance determinations: compliance with EPA's 2024 PFAS limits is judged on running annual averages of compliance monitoring, required from 2029, so a single UCMR 5 result at or above a limit is not a violation. “< MRL” means the compound was not quantified at EPA's minimum reporting level; it does not mean zero.
Water purchased from
- Chester Water Authority (PA1230004)
Seller's highest results: PFOA 5.1 ppt · PFOS <MRL · HI 0.002 · detected: PFBS;PFHxA;PFOA;PFPeA
Seller results are the seller's own entry-point samples, not measurements of this system's water. This system's own samples (below) may reflect purchased water, its own sources, or both.
Compared with EPA's 2024 values
| Highest single result | Worst entry-point average* | Limit | |
|---|---|---|---|
| PFOA (ppt) | 17.7 | 11.75 | 4 |
| PFOS (ppt) | 14.4 | 9.03 | 4 |
| Hazard Index | 0.422 | 0.277 | 1.0† |
“<MRL” = every result for the compound was below its reporting limit. * Mean of all samples at each entry point with non-detects = 0 (EPA compliance convention; the Hazard Index also uses non-detects = 0); a screening comparison, not a formal running annual average. † Rescission proposed May 2026. PFOA/PFOS MCL 4 ppt (2024 NPDWR, in effect). PFHxS, PFNA, HFPO-DA (10 ppt each) and the Hazard Index (1.0) are 2024 NPDWR values; EPA proposed rescinding them on 18 May 2026 (comment period closed 20 Jul 2026).
Compared with Pennsylvania standards
| Highest single result | Worst entry-point average* | Pennsylvania | |
|---|---|---|---|
| PFOA (ppt) | 17.7 | 11.75 | 14 |
| PFOS (ppt) | 14.4 | 9.03 | 18 |
Sum standards add the listed compounds within each sample (non-detects = 0). State compliance is normally judged on averages over time; these are screening comparisons.
Sampling history
Sampled 2023-01-18 to 2024-01-29 · 3 entry point(s) · water types: SW · 17 sampling visits. PFAS in ppt (ng/L).
| Date | Entry point | Event | PFOA | PFOS | HI | Other detections |
|---|---|---|---|---|---|---|
| 2023-01-18 | CHESTER WATER (SW) | SE1 | <4 | <4 | 0 | none |
| 2023-01-18 | N WALNUT RD YARD HYD (SW) | SE1 | <4 | <4 | 0 | none |
| 2023-01-18 | YEATMAN WELL (SW) | SE1 | 14.4 | 14.4 | 0.352 | PFBA 17.8, PFHpA 7.3, PFHxA 10.1, PFPeA 11.2 |
| 2023-04-17 | CHESTER WATER (SW) | SE2 | n/a | n/a | n/a | none |
| 2023-04-17 | N WALNUT RD YARD HYD (SW) | SE2 | <4 | <4 | 0 | none |
| 2023-04-17 | YEATMAN WELL (SW) | SE2 | n/a | n/a | n/a | none |
| 2023-07-05 | CHESTER WATER (SW) | SE2 | <4 | <4 | 0 | PFHxA 3.5, PFPeA 3.9 |
| 2023-07-05 | YEATMAN WELL (SW) | SE2 | 14.9 | 9.2 | 0.332 | PFBA 16.9, PFHpA 6.6, PFHxA 9.5, PFPeA 10.8 |
| 2023-07-17 | CHESTER WATER (SW) | SE3 | <4 | <4 | 0 | PFPeA 3.2 |
| 2023-07-17 | N WALNUT RD YARD HYD (SW) | SE3 | <4 | <4 | 0 | none |
| 2023-07-17 | YEATMAN WELL (SW) | SE3 | 17.7 | 12.5 | 0.422 | PFBA 18.9, PFHpA 7.8, PFHxA 11.4, PFPeA 12.6 |
| 2023-10-11 | CHESTER WATER (SW) | SE4 | <4 | <4 | 0 | none |
| 2023-10-11 | N WALNUT RD YARD HYD (SW) | SE4 | <4 | <4 | 0 | none |
| 2023-10-11 | YEATMAN WELL (SW) | SE4 | <4 | <4 | 0 | none |
| 2024-01-10 | CHESTER WATER (SW) | SE4 | n/a | n/a | n/a | none |
| 2024-01-10 | YEATMAN WELL (SW) | SE4 | n/a | n/a | n/a | none |
| 2024-01-29 | N WALNUT RD YARD HYD (SW) | SE4 | n/a | n/a | n/a | none |
“<4” = not detected at the reporting limit shown; “n/a” = not analyzed in that sample. Highlighted = at or above the 4 ppt MCL. HI computed per sample with non-detects as 0. Other detections lists every other quantified compound (lithium in µg/L).
All results by entry point
360 results. Each column is one sampling visit (date and UCMR 5 sample event). A number is a measured concentration; “< 4” = below the minimum reporting level shown; “–” = not analyzed in that visit. PFAS in ppt (ng/L); lithium in µg/L.
CHESTER WATER facility 100 · sample point EP0001 · surface water
| Compound | MRL | 2023-01-18 SE1 | 2023-04-17 SE2 | 2023-07-05 SE2 | 2023-07-17 SE3 | 2023-10-11 SE4 | 2024-01-10 SE4 |
|---|---|---|---|---|---|---|---|
| PFHxA | 3 ppt | < 3 | – | 3.5 | < 3 | < 3 | – |
| PFPeA | 3 ppt | < 3 | – | 3.9 | 3.2 | < 3 | – |
| 11Cl-PF3OUdS | 5 ppt | < 5 | – | < 5 | < 5 | < 5 | – |
| 4:2 FTS | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| 6:2 FTS | 5 ppt | < 5 | – | < 5 | < 5 | < 5 | – |
| 8:2 FTS | 5 ppt | < 5 | – | < 5 | < 5 | < 5 | – |
| 9Cl-PF3ONS | 2 ppt | < 2 | – | < 2 | < 2 | < 2 | – |
| ADONA | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| HFPO-DA | 5 ppt | < 5 | – | < 5 | < 5 | < 5 | – |
| NEtFOSAA | 5 ppt | < 5 | < 5 | – | < 5 | – | < 5 |
| NFDHA | 20 ppt | < 20 | – | < 20 | < 20 | < 20 | – |
| NMeFOSAA | 6 ppt | < 6 | < 6 | – | < 6 | – | < 6 |
| PFBA | 5 ppt | < 5 | – | < 5 | < 5 | < 5 | – |
| PFBS | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFDA | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFDoA | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFEESA | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFHpA | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFHpS | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFHxS | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFMBA | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFMPA | 4 ppt | < 4 | – | < 4 | < 4 | < 4 | – |
| PFNA | 4 ppt | < 4 | – | < 4 | < 4 | < 4 | – |
| PFOA | 4 ppt | < 4 | – | < 4 | < 4 | < 4 | – |
| PFOS | 4 ppt | < 4 | – | < 4 | < 4 | < 4 | – |
| PFPeS | 4 ppt | < 4 | – | < 4 | < 4 | < 4 | – |
| PFTA | 8 ppt | < 8 | < 8 | – | < 8 | – | < 8 |
| PFTrDA | 7 ppt | < 7 | < 7 | – | < 7 | – | < 7 |
| PFUnA | 2 ppt | < 2 | – | < 2 | < 2 | < 2 | – |
| lithium | 9 µg/L | < 9 | < 9 | – | < 9 | < 9 | – |
N WALNUT RD YARD HYD facility 101 · sample point E · surface water
| Compound | MRL | 2023-01-18 SE1 | 2023-04-17 SE2 | 2023-07-17 SE3 | 2023-10-11 SE4 | 2024-01-29 SE4 |
|---|---|---|---|---|---|---|
| 11Cl-PF3OUdS | 5 ppt | < 5 | < 5 | < 5 | < 5 | – |
| 4:2 FTS | 3 ppt | < 3 | < 3 | < 3 | < 3 | – |
| 6:2 FTS | 5 ppt | < 5 | < 5 | < 5 | < 5 | – |
| 8:2 FTS | 5 ppt | < 5 | < 5 | < 5 | < 5 | – |
| 9Cl-PF3ONS | 2 ppt | < 2 | < 2 | < 2 | < 2 | – |
| ADONA | 3 ppt | < 3 | < 3 | < 3 | < 3 | – |
| HFPO-DA | 5 ppt | < 5 | < 5 | < 5 | < 5 | – |
| NEtFOSAA | 5 ppt | < 5 | < 5 | < 5 | – | < 5 |
| NFDHA | 20 ppt | < 20 | < 20 | < 20 | < 20 | – |
| NMeFOSAA | 6 ppt | < 6 | < 6 | < 6 | – | < 6 |
| PFBA | 5 ppt | < 5 | < 5 | < 5 | < 5 | – |
| PFBS | 3 ppt | < 3 | < 3 | < 3 | < 3 | – |
| PFDA | 3 ppt | < 3 | < 3 | < 3 | < 3 | – |
| PFDoA | 3 ppt | < 3 | < 3 | < 3 | < 3 | – |
| PFEESA | 3 ppt | < 3 | < 3 | < 3 | < 3 | – |
| PFHpA | 3 ppt | < 3 | < 3 | < 3 | < 3 | – |
| PFHpS | 3 ppt | < 3 | < 3 | < 3 | < 3 | – |
| PFHxA | 3 ppt | < 3 | < 3 | < 3 | < 3 | – |
| PFHxS | 3 ppt | < 3 | < 3 | < 3 | < 3 | – |
| PFMBA | 3 ppt | < 3 | < 3 | < 3 | < 3 | – |
| PFMPA | 4 ppt | < 4 | < 4 | < 4 | < 4 | – |
| PFNA | 4 ppt | < 4 | < 4 | < 4 | < 4 | – |
| PFOA | 4 ppt | < 4 | < 4 | < 4 | < 4 | – |
| PFOS | 4 ppt | < 4 | < 4 | < 4 | < 4 | – |
| PFPeA | 3 ppt | < 3 | < 3 | < 3 | < 3 | – |
| PFPeS | 4 ppt | < 4 | < 4 | < 4 | < 4 | – |
| PFTA | 8 ppt | < 8 | < 8 | < 8 | – | < 8 |
| PFTrDA | 7 ppt | < 7 | < 7 | < 7 | – | < 7 |
| PFUnA | 2 ppt | < 2 | < 2 | < 2 | < 2 | – |
| lithium | 9 µg/L | < 9 | < 9 | < 9 | < 9 | – |
YEATMAN WELL facility 102 · sample point E · surface water
| Compound | MRL | 2023-01-18 SE1 | 2023-04-17 SE2 | 2023-07-05 SE2 | 2023-07-17 SE3 | 2023-10-11 SE4 | 2024-01-10 SE4 |
|---|---|---|---|---|---|---|---|
| PFBA | 5 ppt | 17.8 | – | 16.9 | 18.9 | < 5 | – |
| PFBS | 3 ppt | 4.1 | – | 4.1 | 4.5 | < 3 | – |
| PFHpA | 3 ppt | 7.3 | – | 6.6 | 7.8 | < 3 | – |
| PFHxA | 3 ppt | 10.1 | – | 9.5 | 11.4 | < 3 | – |
| PFHxS | 3 ppt | 3.5 | – | 3.3 | 4.2 | < 3 | – |
| PFOA | 4 ppt | 14.4 | – | 14.9 | 17.7 | < 4 | – |
| PFOS | 4 ppt | 14.4 | – | 9.2 | 12.5 | < 4 | – |
| PFPeA | 3 ppt | 11.2 | – | 10.8 | 12.6 | < 3 | – |
| 11Cl-PF3OUdS | 5 ppt | < 5 | – | < 5 | < 5 | < 5 | – |
| 4:2 FTS | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| 6:2 FTS | 5 ppt | < 5 | – | < 5 | < 5 | < 5 | – |
| 8:2 FTS | 5 ppt | < 5 | – | < 5 | < 5 | < 5 | – |
| 9Cl-PF3ONS | 2 ppt | < 2 | – | < 2 | < 2 | < 2 | – |
| ADONA | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| HFPO-DA | 5 ppt | < 5 | – | < 5 | < 5 | < 5 | – |
| NEtFOSAA | 5 ppt | < 5 | < 5 | – | < 5 | – | < 5 |
| NFDHA | 20 ppt | < 20 | – | < 20 | < 20 | < 20 | – |
| NMeFOSAA | 6 ppt | < 6 | < 6 | – | < 6 | – | < 6 |
| PFDA | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFDoA | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFEESA | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFHpS | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFMBA | 3 ppt | < 3 | – | < 3 | < 3 | < 3 | – |
| PFMPA | 4 ppt | < 4 | – | < 4 | < 4 | < 4 | – |
| PFNA | 4 ppt | < 4 | – | < 4 | < 4 | < 4 | – |
| PFPeS | 4 ppt | < 4 | – | < 4 | < 4 | < 4 | – |
| PFTA | 8 ppt | < 8 | < 8 | – | < 8 | – | < 8 |
| PFTrDA | 7 ppt | < 7 | < 7 | – | < 7 | – | < 7 |
| PFUnA | 2 ppt | < 2 | – | < 2 | < 2 | < 2 | – |
| lithium | 9 µg/L | < 9 | < 9 | – | < 9 | < 9 | – |
Statistics by compound
| Compound | Results | Detected | Highest (date) | Mean bounds | KM median | P75 | P90 | P95 |
|---|---|---|---|---|---|---|---|---|
| PFPeA | 12 | 42% | 12.6 2023-07-17 | 3.48–5.22 | <MRL | 3.9 | 11.2 | 12.6 |
| PFHxA | 12 | 33% | 11.4 2023-07-17 | 2.88–4.88 | <MRL | 3.5 | 10.1 | 11.4 |
| PFBA | 12 | 25% | 18.9 2023-07-17 | 4.47–8.22 | <MRL | <MRL | 17.8 | 18.9 |
| PFBS | 12 | 25% | 4.5 2023-07-17 | 1.06–3.31 | <MRL | <MRL | 4.1 | 4.5 |
| PFHpA | 12 | 25% | 7.8 2023-07-17 | 1.81–4.06 | <MRL | <MRL | 7.3 | 7.8 |
| PFHxS | 12 | 25% | 4.2 2023-07-17 | 0.92–3.17 | <MRL | <MRL | 3.5 | 4.2 |
| PFOA | 12 | 25% | 17.7 2023-07-17 | 3.92–6.92 | <MRL | <MRL | 14.9 | 17.7 |
| PFOS | 12 | 25% | 14.4 2023-01-18 | 3.01–6.01 | <MRL | <MRL | 12.5 | 14.4 |
Never detected (22): 11Cl-PF3OUdS, 4:2 FTS, 6:2 FTS, 8:2 FTS, 9Cl-PF3ONS, ADONA, HFPO-DA, NEtFOSAA, NFDHA, NMeFOSAA, PFDA, PFDoA, PFEESA, PFHpS, PFMBA, PFMPA, PFNA, PFPeS, PFTA, PFTrDA, PFUnA, lithium.
Left-censored Kaplan–Meier statistics (Helsel 2005; Helsel & Lee 2006, NADA for R). Units: ppt; lithium µg/L. Each compound has one reporting limit, so the Kaplan–Meier mean equals the upper mean bound (non-detects at the MRL); the lower bound sets non-detects to 0. “<MRL” = the percentile falls below the reporting limit and cannot be estimated. These describe this system's UCMR 5 samples, not population estimates.
Sources
- EPA UCMR 5 occurrence data text files (UCMR5_All.txt; samples 2023-01-10 to 2026-04-09; data summary dated Jul 2026)
- EPA SDWIS via ECHO SDWA downloads, quarter 2026Q3
- EPA Public Water System Service Areas v3 (Mar 2026)
- US Census Bureau cartographic boundary counties 1:500k, 2024
- EPA/USGS NHDPlus V2 (medium resolution) flowlines, Strahler order 2+
Data build 52bd2907cbc3 · 2026-10-18T04:10Z · UCMR 5 release Jul2026 · SDWIS 2026Q3. Data and methods.