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Tap water quality report

Sonoma County Mutual Water Company

EPA monitoring tested this supplier for 55 contaminants and detected 13. A detection doesn't automatically mean the water is unsafe — the level and EPA source for each is below.

55
contaminants tested
13
detected
40
people served
168
health-based violations
California rankingsLead in CaliforniaPFAS in California
Water source
Ground water under surface influence
Ownership
Private
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.

168
health-based violations
208
violations on file
0
still open
ViolationTypeStatusPeriod
TT Health-based Resolved 2020-07-23
TT Health-based Resolved 2020-07-23
TT Health-based Resolved 2019-08-01
TT Health-based Resolved 2019-08-01
TT Health-based Resolved 2019-07-01
TT Health-based Resolved 2019-07-01
TT Health-based Resolved 2019-06-01
TT Health-based Resolved 2019-06-01
TT Health-based Resolved 2019-05-01
TT Health-based Resolved 2019-05-01

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
Lead
0.0028 mg/L 19%
of the EPA limit 0.0150 mg/L
 17/17 LCR 2023
Nitrate
1288.2 µg/L 13%
of the EPA limit 10000 µg/L
 14/16 SYR4 2012–2019
Bromodichloromethane
2.375 µg/L
No EPA limit set
worst single sample: 2.5 µg/L
6/8 SYR4 2013–2019
Dibromochloromethane
2.4 µg/L
No EPA limit set
worst single sample: 2.6 µg/L
6/8 SYR4 2013–2019
Fluoride
250 µg/L 6.3%
of the EPA limit 4000 µg/L
worst single sample: 280 µg/L
6/7 SYR4 2013–2019
TTHM
5.25 µg/L 6.6%
of the EPA limit 80 µg/L
worst single sample: 5.3 µg/L
6/8 SYR4 2013–2019
Chromium
1.37 µg/L 1.4%
of the EPA limit 100 µg/L
worst single sample: 1.4 µg/L
3/7 SYR4 2013–2019
Total Haloacetic Acids (HAA5)
3.9805 µg/L 6.6%
of the EPA limit 60 µg/L
worst single sample: 4.1 µg/L
2/8 SYR4 2013–2019
Barium
140 µg/L 7%
of the EPA limit 2000 µg/L
 1/7 SYR4 2013–2019
Copper
7800 µg/L 600%
of the EPA limit, at the 95th percentile of samples — 1300 µg/L
 1/17 SYR4 2013–2019
Chloroform
1.5 µg/L
No EPA limit set
 1/8 SYR4 2013–2019
Dibromoacetic Acid
1.71 µg/L
No EPA limit set
 1/8 SYR4 2013–2019
Monochloroacetic Acid
4.1 µg/L
No EPA limit set
 1/8 SYR4 2013–2019
42 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-Dichloroethane1,2-Dichloropropane2,4,5-TP2,4-DAntimony, TotalArsenicAsbestosAtrazineBenzeneBeryllium, TotalBromoformChlorobenzeneCadmiumCarbon TetrachlorideDichloromethaneDalaponDichloroacetic AcidDinosebEthylbenzeneMercuryMonobromoacetic AcidNitritePentachlorophenolPicloramSeleniumSimazineStyreneTetrachloroethyleneThallium, TotalTolueneTrichloroacetic AcidTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact
WILLIAMSON, MIKE
Phone
415-902-9028
Email
presidentscmwc@gmail.com

Frequently asked questions about Sonoma County Mutual Water Company

Is Sonoma County Mutual Water Company tap water safe to drink?

EPA monitoring detected 13 contaminants in Sonoma County Mutual Water Company'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 Mutual Water Company's water?

EPA monitoring detected Lead, Nitrate, Bromodichloromethane, Dibromochloromethane, Fluoride, and others. The full list with the level and data source for each is above.

How many people does Sonoma County Mutual Water Company serve?

Sonoma County Mutual Water Company reports serving 40 people in California, per its EPA record.

Has Sonoma County Mutual Water Company had any water quality violations?

The EPA has 208 violations on file for Sonoma County Mutual Water Company, of which 168 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.