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Tap water quality report

Issaquah Water

EPA monitoring tested this supplier for 88 contaminants and detected 15. A detection doesn't automatically mean the water is unsafe — the level and EPA source for each is below.

88
contaminants tested
15
detected
43,584
people served
8
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.

8
health-based violations
256
violations on file
0
still open
ViolationTypeStatusPeriod
MCL Health-based Archived 2003-11-01 → 2003-11-30
MCL Health-based Archived 2000-12-01 → 2000-12-31
MCL Health-based Archived 2000-12-01 → 2000-12-31
MCL Health-based Archived 2000-12-01 → 2000-12-31
MCL Health-based Archived 2000-11-01 → 2000-11-30
MCL Health-based Archived 2000-11-01 → 2000-11-30
MCL Health-based Archived 2000-11-01 → 2000-11-30
MCL Health-based Archived 1994-08-01 → 1994-08-31
Other Monitoring Resolved 2015-07-01
MR Monitoring Resolved 2005-01-01 → 2007-12-31

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
Chloroform
46.44 µg/L
No EPA limit set
worst single sample: 59.5 µg/L
129/136 SYR4 2012–2019
TTHM
49.44 µg/L 62%
of the EPA limit 80 µg/L
worst single sample: 63.3 µg/L
129/129 SYR4 2012–2019
Dichloroacetic Acid
17.14 µg/L
No EPA limit set
worst single sample: 24 µg/L
127/128 SYR4 2012–2019
Total Haloacetic Acids (HAA5)
37.87 µg/L 63%
of the EPA limit 60 µg/L
worst single sample: 56.6 µg/L
127/130 SYR4 2012–2019
Trichloroacetic Acid
23.775 µg/L
No EPA limit set
worst single sample: 28.7 µg/L
122/128 SYR4 2012–2019
Bromodichloromethane
3.2 µg/L
No EPA limit set
worst single sample: 3.8 µg/L
111/119 SYR4 2012–2019
Nitrate
655.5 µg/L 6.6%
of the EPA limit 10000 µg/L
worst single sample: 660 µg/L
30/36 SYR4 2012–2019
Monochloroacetic Acid
3.305 µg/L
No EPA limit set
worst single sample: 3.9 µg/L
18/130 SYR4 2012–2019
Lead
0.0010 mg/L 6.7%
of the EPA limit 0.0150 mg/L
 15/15 LCR 2022
Dibromochloromethane
2.48 µg/L
No EPA limit set
worst single sample: 2.6 µg/L
9/132 SYR4 2012–2019
Arsenic
8.1 µg/L 81%
of the EPA limit 10 µg/L
worst single sample: 9 µg/L
4/4 SYR4 2016
Barium
11.95 µg/L 0.6%
of the EPA limit 2000 µg/L
worst single sample: 13 µg/L
4/4 SYR4 2016
Nitrate-Nitrite
535 µg/L 5.4%
of the EPA limit 10000 µg/L
worst single sample: 540 µg/L
3/4 SYR4 2016
Bromoform
0.5000 µg/L
No EPA limit set
 1/135 SYR4 2012–2019
Copper
5 µg/L 0.4%
of the EPA limit 1300 µg/L
 1/4 SYR4 2016
73 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, TotalBenzeneBeryllium, TotalChlorobenzeneCyanideCadmiumCarbon TetrachlorideChromiumDichloromethaneDalaponDibromoacetic AcidDinosebEthylene DibromideEthylbenzeneFluorideGross Beta Particle ActivityHfpo-DaLeadMercuryMonobromoacetic AcidNetfosaaNfdhaNmefosaaNitritePfbaPFBSPfdaPfdoaPfeesaPfhpaPfhpsPfhxaPFHXSPfmbaPfmpaPFNAPFOAPFOSPfpeaPfpesPftaPftrdaPfunaPentachlorophenolPicloramSeleniumStyreneTetrachloroethyleneThallium, TotalTolueneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneLithiumO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact
Gabrielle Wolff

Frequently asked questions about Issaquah Water

Is Issaquah Water tap water safe to drink?

EPA monitoring detected 15 contaminants in Issaquah Water'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 Issaquah Water's water?

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

How many people does Issaquah Water serve?

Issaquah Water reports serving 43,584 people in Washington, per its EPA record.

Has Issaquah Water had any water quality violations?

The EPA has 256 violations on file for Issaquah Water, of which 8 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.