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Sammamish Plateau Water & Sewer

EPA monitoring tested this supplier for 106 contaminants and detected 25. A detection doesn't automatically mean the water is unsafe — the level and EPA source for each is below.

106
contaminants tested
25
detected
79,362
people served
5
health-based violations
Washington rankingsLead in WashingtonPFAS in Washington
Water source
SWP
Ownership
Local government
Counties served
King

Compliance record

Formal violations the EPA has on file for this supplier. A health-based violation means a contaminant limit or a required treatment was breached; the rest are monitoring or reporting failures — still violations, but not a measured health risk.

5
health-based violations
76
violations on file
0
still open
ViolationTypeStatusPeriod
MCL Health-based Archived 2004-01-01 → 2004-01-31
MCL Health-based Archived 2000-08-01 → 2000-08-31
MCL Health-based Archived 2000-08-01 → 2000-08-31
MCL Health-based Archived 2000-08-01 → 2000-08-31
MCL Health-based Archived 1992-06-01 → 1992-06-30
MR Monitoring Resolved 2009-01-01 → 2009-12-31
MR Monitoring Resolved 2009-01-01 → 2009-12-31
MR Monitoring Archived 2008-04-01 → 2008-06-30
MR Monitoring Archived 2008-04-01 → 2008-06-30
MR Monitoring Archived 2008-04-01 → 2008-06-30

PFAS detected

PFAS are industrial “forever chemicals”. These are the EPA's latest nationwide test results (2023–2025).
ContaminantMaxDetection ratePeriod
PFHXS 0.0165 µg/L 9/16 2024
PFBS 0.0088 µg/L 6/16 2024
PFOS 0.0111 µg/L 4/16 2024
Pfhxa 0.0043 µg/L 2/16 2024
Pfpea 0.0039 µg/L 2/16 2024
Pfpes 0.0041 µg/L 1/16 2024

Other contaminants detected

Each bar shows the measured level as a share of the EPA limit: green is well under, amber is close to it, red is over. For lead and copper the limit applies to exactly the 90th-percentile figure shown, so red there means a real exceedance. For everything else the limit applies to a running annual average while the figure is the 95th percentile of this system's samples — over 100% is worth reading, but is not by itself a violation. Where a single sample came in higher than that percentile, it is noted under the bar. Formal violations are listed separately.
ContaminantLevel vs EPA limitDetection rateSourcePeriod
TTHM
45.31 µg/L 57%
of the EPA limit 80 µg/L
worst single sample: 73.07 µg/L
259/259 SYR4 2012–2019
Chloroform
41.475 µg/L
No EPA limit set
worst single sample: 67.7 µg/L
258/267 SYR4 2012–2019
Total Haloacetic Acids (HAA5)
38.382 µg/L 64%
of the EPA limit 60 µg/L
worst single sample: 49.9 µg/L
249/249 SYR4 2012–2019
Trichloroacetic Acid
22.11 µg/L
No EPA limit set
worst single sample: 29.6 µg/L
247/247 SYR4 2012–2019
Bromodichloromethane
3.7 µg/L
No EPA limit set
worst single sample: 8.27 µg/L
244/259 SYR4 2012–2019
Dichloroacetic Acid
17.97 µg/L
No EPA limit set
worst single sample: 23.6 µg/L
239/244 SYR4 2012–2019
Dibromochloromethane
1.982 µg/L
No EPA limit set
worst single sample: 3.2 µg/L
119/257 SYR4 2012–2019
Nitrate
2233.5 µg/L 22%
of the EPA limit 10000 µg/L
worst single sample: 2300 µg/L
80/130 SYR4 2012–2019
Monochloroacetic Acid
3.2955 µg/L
No EPA limit set
worst single sample: 4.2 µg/L
30/248 SYR4 2012–2019
Lead
0.0017 mg/L 11%
of the EPA limit 0.0150 mg/L
 24/24 LCR 2025
Fluoride
800 µg/L 20%
of the EPA limit 4000 µg/L
 14/18 SYR4 2012–2018
Arsenic
6.39 µg/L 64%
of the EPA limit 10 µg/L
worst single sample: 6.6 µg/L
8/18 SYR4 2012–2018
Nitrate-Nitrite
1728.5 µg/L 17%
of the EPA limit 10000 µg/L
worst single sample: 1900 µg/L
8/18 SYR4 2012–2018
Dibromoacetic Acid
0.6603 µg/L
No EPA limit set
worst single sample: 0.6660 µg/L
6/250 SYR4 2012–2019
Copper
30.9 µg/L 2.4%
of the EPA limit 1300 µg/L
worst single sample: 31 µg/L
3/18 SYR4 2012–2018
Bromoform
0.6475 µg/L
No EPA limit set
worst single sample: 0.6500 µg/L
2/268 SYR4 2012–2019
Lead
3.9 µg/L 26%
of the EPA limit 15 µg/L
worst single sample: 4 µg/L
2/18 SYR4 2012–2018
Asbestos
0.1150 MFL 1.6%
of the EPA limit 7 MFL
 1/1 SYR4 2017
Cadmium
0.2000 µg/L 4%
of the EPA limit 5 µg/L
 1/18 SYR4 2012–2018
81 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-Dichloropropane11Cl-PF3OUdS2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAntimony, TotalAtrazineBhc-GammaBariumBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCyanideCarbofuranCarbon TetrachlorideChlordaneChromiumDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebEthylene DibromideEndrinEthylbenzeneHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMercuryMethoxychlorMonobromoacetic AcidNetfosaaNfdhaNmefosaaNitriteOxamylPfbaPfdaPfdoaPfeesaPfhpaPfhpsPfmbaPfmpaPFNAPFOAPftaPftrdaPfunaPentachlorophenolPicloramSeleniumSimazineStyreneTetrachloroethyleneThallium, TotalTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneLithiumO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact
Andrew Tuchscherer

Frequently asked questions about Sammamish Plateau Water & Sewer

Is Sammamish Plateau Water & Sewer tap water safe to drink?

EPA monitoring detected 25 contaminants in Sammamish Plateau Water & Sewer's water. A detection isn't the same as a violation — most levels are within federal limits. See each level and source above, and the utility's annual Consumer Confidence Report for its official compliance status.

What contaminants were detected in Sammamish Plateau Water & Sewer's water?

EPA monitoring detected TTHM, Chloroform, Total Haloacetic Acids (HAA5), Trichloroacetic Acid, Bromodichloromethane, and others. The full list with the level and data source for each is above.

How many people does Sammamish Plateau Water & Sewer serve?

Sammamish Plateau Water & Sewer reports serving 79,362 people in Washington, per its EPA record.

Has Sammamish Plateau Water & Sewer had any water quality violations?

The EPA has 76 violations on file for Sammamish Plateau Water & Sewer, of which 5 are health-based (a contaminant limit or required treatment was breached) and 0 remain open. The rest are monitoring or reporting failures.

Where does this data come from?

Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.