Dcwa Knightsville (Sc1820001)

PFAS monitoring results for a public water system in South Carolina

SC1820001UCMR 5EPA monitoring data
6.5Highest PFOA result, ppt
8.1Highest PFOS result, ppt
0.002Highest Hazard Index
360Results
PWSID
SC1820001
State
South Carolina
System type
community water system (CWS)
Population served
40,141
City
Summerville
Counties
Dorchester County
Primary source water
surface water (purchased)
UCMR 5 sampling
2024-09-11 to 2025-09-24 · 5 entry point(s) · water types: GW;SW
Service-area boundary
EPA-modeled (Random Forest) — approximate: estimated by EPA with a statistical model, not a surveyed service area

PFOS 1–3 × its limit highest single result
PFOS 1–3 × its limit worst entry-point average

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

  • Summerville Cpw (Sc1810003) (SC1810003)
    Seller's highest results: PFOA 6.2 ppt · PFOS 8.1 ppt · HI 0.002 · detected: PFBA;PFBS;PFHxA;PFOA;PFOS;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 resultWorst entry-point average*Limit
PFOA (ppt)6.55.854
PFOS (ppt)8.17.174
Hazard Index0.0020.0021.0†

“<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).

No South Carolina PFAS drinking-water standard in effect or proposed as of 2026-10-17: No state PFAS drinking-water standard; H. 3116 and H. 5572 (2025-26) pending, not enacted.

Sampling history

Sampled 2024-09-11 to 2025-09-24 · 5 entry point(s) · water types: GW;SW · 13 sampling visits. PFAS in ppt (ng/L).

DateEntry pointEventPFOAPFOSHIOther detections
2024-09-11PLANT 8(B18011) WELL (G18101) BACONS BRIDGE (GW)SE1<4<40lithium 11.3 µg/L
2024-09-11PLANT 9 (B18012) WELL 9 (G18235) CANE ACRE RD (GW)SE1<4<40lithium 12.7 µg/L
2024-09-11Plant 1 (B18001) WELL 1 (G18113) DORCHESTER (GW)SE1<4<40lithium 12.2 µg/L
2024-09-11Summerville CPW - Connection (SW)SE167.90.002PFBA 5, PFHxA 6.2, PFPeA 7.2
2024-09-11Treatment Plant (GW)SE1<4<40lithium 11.4 µg/L
2024-12-16PLANT 9 (B18012) WELL 9 (G18235) CANE ACRE RD (GW)SE2<4<40lithium 11 µg/L
2024-12-16Plant 1 (B18001) WELL 1 (G18113) DORCHESTER (GW)SE2<4<40lithium 11.5 µg/L
2024-12-16Summerville CPW - Connection (SW)SE2n/an/an/anone
2024-12-16Treatment Plant (GW)SE2<4<40lithium 9.25 µg/L
2024-12-18PLANT 8(B18011) WELL (G18101) BACONS BRIDGE (GW)SE2<4<40lithium 11.6 µg/L
2025-02-14Summerville CPW - Connection (SW)SE35.55.80.002PFHxA 5, PFPeA 5.5
2025-06-24Summerville CPW - Connection (SW)SE45.46.90.002PFHxA 4.8, PFPeA 5.1
2025-09-24Summerville CPW - Connection (SW)SE26.58.10.002PFHpA 3, PFHxA 6.1, PFPeA 7

“<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.

PLANT 8(B18011) WELL (G18101) BACONS BRIDGE facility 18011 · sample point B18011 · groundwater

CompoundMRL2024-09-11
SE1
2024-12-18
SE2
11Cl-PF3OUdS5 ppt< 5< 5
4:2 FTS3 ppt< 3< 3
6:2 FTS5 ppt< 5< 5
8:2 FTS5 ppt< 5< 5
9Cl-PF3ONS2 ppt< 2< 2
ADONA3 ppt< 3< 3
HFPO-DA5 ppt< 5< 5
NEtFOSAA5 ppt< 5< 5
NFDHA20 ppt< 20< 20
NMeFOSAA6 ppt< 6< 6
PFBA5 ppt< 5< 5
PFBS3 ppt< 3< 3
PFDA3 ppt< 3< 3
PFDoA3 ppt< 3< 3
PFEESA3 ppt< 3< 3
PFHpA3 ppt< 3< 3
PFHpS3 ppt< 3< 3
PFHxA3 ppt< 3< 3
PFHxS3 ppt< 3< 3
PFMBA3 ppt< 3< 3
PFMPA4 ppt< 4< 4
PFNA4 ppt< 4< 4
PFOA4 ppt< 4< 4
PFOS4 ppt< 4< 4
PFPeA3 ppt< 3< 3
PFPeS4 ppt< 4< 4
PFTA8 ppt< 8< 8
PFTrDA7 ppt< 7< 7
PFUnA2 ppt< 2< 2
lithium9 µg/L11.311.6

PLANT 9 (B18012) WELL 9 (G18235) CANE ACRE RD facility 18012 · sample point B18012 · groundwater

CompoundMRL2024-09-11
SE1
2024-12-16
SE2
11Cl-PF3OUdS5 ppt< 5< 5
4:2 FTS3 ppt< 3< 3
6:2 FTS5 ppt< 5< 5
8:2 FTS5 ppt< 5< 5
9Cl-PF3ONS2 ppt< 2< 2
ADONA3 ppt< 3< 3
HFPO-DA5 ppt< 5< 5
NEtFOSAA5 ppt< 5< 5
NFDHA20 ppt< 20< 20
NMeFOSAA6 ppt< 6< 6
PFBA5 ppt< 5< 5
PFBS3 ppt< 3< 3
PFDA3 ppt< 3< 3
PFDoA3 ppt< 3< 3
PFEESA3 ppt< 3< 3
PFHpA3 ppt< 3< 3
PFHpS3 ppt< 3< 3
PFHxA3 ppt< 3< 3
PFHxS3 ppt< 3< 3
PFMBA3 ppt< 3< 3
PFMPA4 ppt< 4< 4
PFNA4 ppt< 4< 4
PFOA4 ppt< 4< 4
PFOS4 ppt< 4< 4
PFPeA3 ppt< 3< 3
PFPeS4 ppt< 4< 4
PFTA8 ppt< 8< 8
PFTrDA7 ppt< 7< 7
PFUnA2 ppt< 2< 2
lithium9 µg/L12.711

Plant 1 (B18001) WELL 1 (G18113) DORCHESTER facility 18001 · sample point B18001 · groundwater

CompoundMRL2024-09-11
SE1
2024-12-16
SE2
11Cl-PF3OUdS5 ppt< 5< 5
4:2 FTS3 ppt< 3< 3
6:2 FTS5 ppt< 5< 5
8:2 FTS5 ppt< 5< 5
9Cl-PF3ONS2 ppt< 2< 2
ADONA3 ppt< 3< 3
HFPO-DA5 ppt< 5< 5
NEtFOSAA5 ppt< 5< 5
NFDHA20 ppt< 20< 20
NMeFOSAA6 ppt< 6< 6
PFBA5 ppt< 5< 5
PFBS3 ppt< 3< 3
PFDA3 ppt< 3< 3
PFDoA3 ppt< 3< 3
PFEESA3 ppt< 3< 3
PFHpA3 ppt< 3< 3
PFHpS3 ppt< 3< 3
PFHxA3 ppt< 3< 3
PFHxS3 ppt< 3< 3
PFMBA3 ppt< 3< 3
PFMPA4 ppt< 4< 4
PFNA4 ppt< 4< 4
PFOA4 ppt< 4< 4
PFOS4 ppt< 4< 4
PFPeA3 ppt< 3< 3
PFPeS4 ppt< 4< 4
PFTA8 ppt< 8< 8
PFTrDA7 ppt< 7< 7
PFUnA2 ppt< 2< 2
lithium9 µg/L12.211.5

Summerville CPW - Connection facility 18131 · sample point P18131 · surface water

CompoundMRL2024-09-11
SE1
2024-12-16
SE2
2025-02-14
SE3
2025-06-24
SE4
2025-09-24
SE2
PFBA5 ppt5–< 5< 5< 5
PFBS3 ppt4.2–4.13.54.6
PFHpA3 ppt< 3–< 3< 33
PFHxA3 ppt6.2–54.86.1
PFOA4 ppt6–5.55.46.5
PFOS4 ppt7.9–5.86.98.1
PFPeA3 ppt7.2–5.55.17
11Cl-PF3OUdS5 ppt< 5–< 5< 5< 5
4:2 FTS3 ppt< 3–< 3< 3< 3
6:2 FTS5 ppt< 5–< 5< 5< 5
8:2 FTS5 ppt< 5–< 5< 5< 5
9Cl-PF3ONS2 ppt< 2–< 2< 2< 2
ADONA3 ppt< 3–< 3< 3< 3
HFPO-DA5 ppt< 5–< 5< 5< 5
NEtFOSAA5 ppt< 5< 5< 5< 5–
NFDHA20 ppt< 20–< 20< 20< 20
NMeFOSAA6 ppt< 6< 6< 6< 6–
PFDA3 ppt< 3–< 3< 3< 3
PFDoA3 ppt< 3–< 3< 3< 3
PFEESA3 ppt< 3–< 3< 3< 3
PFHpS3 ppt< 3–< 3< 3< 3
PFHxS3 ppt< 3–< 3< 3< 3
PFMBA3 ppt< 3–< 3< 3< 3
PFMPA4 ppt< 4–< 4< 4< 4
PFNA4 ppt< 4–< 4< 4< 4
PFPeS4 ppt< 4–< 4< 4< 4
PFTA8 ppt< 8< 8< 8< 8–
PFTrDA7 ppt< 7< 7< 7< 7–
PFUnA2 ppt< 2–< 2< 2< 2
lithium9 µg/L< 9< 9< 9< 9–

Treatment Plant facility 18007 · sample point B18007 · groundwater

CompoundMRL2024-09-11
SE1
2024-12-16
SE2
11Cl-PF3OUdS5 ppt< 5< 5
4:2 FTS3 ppt< 3< 3
6:2 FTS5 ppt< 5< 5
8:2 FTS5 ppt< 5< 5
9Cl-PF3ONS2 ppt< 2< 2
ADONA3 ppt< 3< 3
HFPO-DA5 ppt< 5< 5
NEtFOSAA5 ppt< 5< 5
NFDHA20 ppt< 20< 20
NMeFOSAA6 ppt< 6< 6
PFBA5 ppt< 5< 5
PFBS3 ppt< 3< 3
PFDA3 ppt< 3< 3
PFDoA3 ppt< 3< 3
PFEESA3 ppt< 3< 3
PFHpA3 ppt< 3< 3
PFHpS3 ppt< 3< 3
PFHxA3 ppt< 3< 3
PFHxS3 ppt< 3< 3
PFMBA3 ppt< 3< 3
PFMPA4 ppt< 4< 4
PFNA4 ppt< 4< 4
PFOA4 ppt< 4< 4
PFOS4 ppt< 4< 4
PFPeA3 ppt< 3< 3
PFPeS4 ppt< 4< 4
PFTA8 ppt< 8< 8
PFTrDA7 ppt< 7< 7
PFUnA2 ppt< 2< 2
lithium9 µg/L11.49.25

Statistics by compound

CompoundResultsDetectedHighest (date)Mean boundsKM medianP75P90P95
lithium1267%12.7
2024-09-11
7.58–10.581111.512.212.7
PFBS1233%4.6
2025-09-24
1.37–3.37<MRL3.54.24.6
PFHxA1233%6.2
2024-09-11
1.84–3.84<MRL4.86.16.2
PFOA1233%6.5
2025-09-24
1.95–4.62<MRL5.466.5
PFOS1233%8.1
2025-09-24
2.39–5.06<MRL5.87.98.1
PFPeA1233%7.2
2024-09-11
2.07–4.07<MRL5.177.2
PFBA128%5
2024-09-11
0.42–5<MRL<MRL<MRL5
PFHpA128%3
2025-09-24
0.25–3<MRL<MRL<MRL3

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, PFHxS, PFMBA, PFMPA, PFNA, PFPeS, PFTA, PFTrDA, PFUnA.

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 2023-01-09 to 2026-06-15; 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 04c4b5704fe9 · 2026-10-18T04:07Z · UCMR 5 release Jul2026 · SDWIS 2026Q3. Data and methods.