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Tap water quality report

Sonoma County Water Agency

EPA monitoring tested this supplier for 79 contaminants and detected 17. A detection doesn't automatically mean the water is unsafe — the level and EPA source for each is below.

79
contaminants tested
17
detected
0
people served
2
health-based violations
California rankingsLead in CaliforniaPFAS in California
Water source
Ground water
Ownership
Local government
Counties served
Sonoma

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.

2
health-based violations
3
violations on file
0
still open
ViolationTypeStatusPeriod
MCL Health-based Resolved 1994-01-01 → 1994-01-31
MCL Health-based Resolved 1994-01-01 → 1994-01-31
MR Monitoring Resolved 1993-07-01 → 2003-12-31

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
11.389 µg/L
No EPA limit set
worst single sample: 17.49 µg/L
575/600 SYR4 2012–2019
TTHM
20.397 µg/L 25%
of the EPA limit 80 µg/L
worst single sample: 27.53 µg/L
575/600 SYR4 2012–2019
Bromodichloromethane
5.98 µg/L
No EPA limit set
worst single sample: 7.41 µg/L
574/599 SYR4 2012–2019
Total Haloacetic Acids (HAA5)
11.812 µg/L 20%
of the EPA limit 60 µg/L
worst single sample: 31.81 µg/L
567/575 SYR4 2012–2019
Dichloroacetic Acid
5.524 µg/L
No EPA limit set
worst single sample: 11.11 µg/L
553/573 SYR4 2012–2019
Dibromochloromethane
4.692 µg/L
No EPA limit set
worst single sample: 5.76 µg/L
550/598 SYR4 2012–2019
Dibromoacetic Acid
2.8 µg/L
No EPA limit set
worst single sample: 13.03 µg/L
453/564 SYR4 2012–2019
Trichloroacetic Acid
4.275 µg/L
No EPA limit set
worst single sample: 6.4 µg/L
431/555 SYR4 2012–2019
Bromoform
2.72 µg/L
No EPA limit set
worst single sample: 2.99 µg/L
206/560 SYR4 2012–2019
Fluoride
176 µg/L 4.4%
of the EPA limit 4000 µg/L
worst single sample: 200 µg/L
49/98 SYR4 2012–2019
Nitrate
358.21 µg/L 3.6%
of the EPA limit 10000 µg/L
worst single sample: 361.6 µg/L
24/196 SYR4 2012–2019
Monochloroacetic Acid
2.637 µg/L
No EPA limit set
worst single sample: 2.7 µg/L
10/513 SYR4 2012–2019
Monobromoacetic Acid
2 µg/L
No EPA limit set
 9/513 SYR4 2012–2019
Arsenic
5.76 µg/L 58%
of the EPA limit 10 µg/L
worst single sample: 6 µg/L
7/104 SYR4 2012–2019
Benzo(A)Pyrene
0.1480 µg/L 74%
of the EPA limit 0.2000 µg/L
worst single sample: 0.1500 µg/L
2/100 SYR4 2012–2019
Asbestos
0.2000 MFL 2.9%
of the EPA limit 7 MFL
 1/73 SYR4 2012–2019
Toluene
12.24 µg/L 1.2%
of the EPA limit 1000 µg/L
 1/675 SYR4 2012–2019
62 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-Dichloropropane2,3,7,8-TCDD2,4,5-TP2,4-DAntimony, TotalAtrazineBhc-GammaBariumBenzeneBeryllium, TotalChlorobenzeneCopperCyanideCadmiumCarbofuranCarbon TetrachlorideChlordaneChromiumDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateHexachlorobenzeneHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoLeadMercuryMethoxychlorNitrate-NitriteNitriteOxamylPentachlorophenolPicloramSeleniumSimazineStyreneTetrachloroethyleneThallium, TotalTotal Polychlorinated Biphenyls (PCB)ToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact
DAVIS, GRANT
Phone
707-547-1911
Email
[email protected]

Frequently asked questions about Sonoma County Water Agency

Is Sonoma County Water Agency tap water safe to drink?

EPA monitoring detected 17 contaminants in Sonoma County Water Agency'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 Sonoma County Water Agency's water?

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

How many people does Sonoma County Water Agency serve?

Sonoma County Water Agency reports serving 0 people in California, per its EPA record.

Has Sonoma County Water Agency had any water quality violations?

The EPA has 3 violations on file for Sonoma County Water Agency, of which 2 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.