Kent Water Department

PFAS monitoring results for a public water system in Washington

WA5338150UCMR 5EPA monitoring data
<MRLHighest PFOA result, ppt
<MRLHighest PFOS result, ppt
0.002Highest Hazard Index
420Results
PWSID
WA5338150
State
Washington
System type
community water system (CWS)
Population served
166,421
City
Kent
Counties
King County
Primary source water
surface water (purchased)
UCMR 5 sampling
2025-01-27 to 2025-12-04 · 6 entry point(s) · water types: GW;SW
Service-area boundary
authoritative

Hazard Index below its limit highest single result
Hazard Index below 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

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)<MRL04
PFOS (ppt)<MRL04
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).

Compared with Washington standards

Highest single resultWorst entry-point average*Washington
PFOA (ppt)004
PFOS (ppt)004
PFNA (ppt)0010
PFHxS (ppt)0010
HFPO-DA (GenX) (ppt)0010

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 2025-01-27 to 2025-12-04 · 6 entry point(s) · water types: GW;SW · 15 sampling visits. PFAS in ppt (ng/L).

DateEntry pointEventPFOAPFOSHIOther detections
2025-01-27East Hill Well (GW)SE1n/an/an/anone
2025-01-27SSP3 (SW)SE1<4<40none
2025-01-27Wells @ 208th & 212th Streets Blending Point (GW)SE1<4<40none
2025-02-04East Hill Well (GW)SE1<4<40.002none
2025-04-29Clark Springs & Armstrong Springs Blending Point (GW)SE1<4<40none
2025-05-22Garrison Creek Well & Clark Springs Blending Point (GW)SE1<4<40none
2025-05-22Kent Springs & Soos Creek Blending Point (GW)SE1<4<40none
2025-05-22SSP3 (SW)SE2<4<40none
2025-07-17SSP3 (SW)SE3<4<40none
2025-07-17Wells @ 208th & 212th Streets Blending Point (GW)SE2<4<40none
2025-10-21Clark Springs & Armstrong Springs Blending Point (GW)SE2<4<40none
2025-10-21East Hill Well (GW)SE2<4<40.002none
2025-10-21SSP3 (SW)SE4<4<40none
2025-12-04Garrison Creek Well & Clark Springs Blending Point (GW)SE2<4<40none
2025-12-04Kent Springs & Soos Creek Blending Point (GW)SE2<4<40none

“<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

420 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.

Clark Springs & Armstrong Springs Blending Point facility 00002 · sample point 00002 · groundwater

CompoundMRL2025-04-29
SE1
2025-10-21
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/L< 9< 9

East Hill Well facility 00005 · sample point 00003 · groundwater

CompoundMRL2025-01-27
SE1
2025-02-04
SE1
2025-10-21
SE2
PFBS3 ppt–3.43.5
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
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/L< 9–< 9

Garrison Creek Well & Clark Springs Blending Point facility 00006 · sample point 00005 · groundwater

CompoundMRL2025-05-22
SE1
2025-12-04
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/L< 9< 9

Kent Springs & Soos Creek Blending Point facility 00001 · sample point 00001 · groundwater

CompoundMRL2025-05-22
SE1
2025-12-04
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/L< 9< 9

SSP3 facility 00019 · sample point 00007 · surface water

CompoundMRL2025-01-27
SE1
2025-05-22
SE2
2025-07-17
SE3
2025-10-21
SE4
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
PFBA5 ppt< 5< 5< 5< 5
PFBS3 ppt< 3< 3< 3< 3
PFDA3 ppt< 3< 3< 3< 3
PFDoA3 ppt< 3< 3< 3< 3
PFEESA3 ppt< 3< 3< 3< 3
PFHpA3 ppt< 3< 3< 3< 3
PFHpS3 ppt< 3< 3< 3< 3
PFHxA3 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
PFOA4 ppt< 4< 4< 4< 4
PFOS4 ppt< 4< 4< 4< 4
PFPeA3 ppt< 3< 3< 3< 3
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

Wells @ 208th & 212th Streets Blending Point facility 00010 · sample point 00004 · groundwater

CompoundMRL2025-01-27
SE1
2025-07-17
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/L< 9< 9

Statistics by compound

CompoundResultsDetectedHighest (date)Mean boundsKM medianP75P90P95
PFBS1414%3.5
2025-10-21
0.49–3.06<MRL<MRL3.43.5

Never detected (29): 11Cl-PF3OUdS, 4:2 FTS, 6:2 FTS, 8:2 FTS, 9Cl-PF3ONS, ADONA, HFPO-DA, NEtFOSAA, NFDHA, NMeFOSAA, PFBA, PFDA, PFDoA, PFEESA, PFHpA, PFHpS, PFHxA, PFHxS, PFMBA, PFMPA, PFNA, PFOA, PFOS, PFPeA, 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 2023-01-23 to 2026-05-19; 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 0fe9c0996add · 2026-10-18T04:09Z · UCMR 5 release Jul2026 · SDWIS 2026Q3. Data and methods.