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San Marcos Mutual Water Company

EPA monitoring tested this supplier for 43 contaminants and detected 9. A detection doesn't automatically mean the water is unsafe — the level and EPA source for each is below.

43
contaminants tested
9
detected
120
people served
8
health-based violations
California rankingsLead in CaliforniaPFAS in California
Water source
Ground water under surface influence
Ownership
Private
Counties served
Santa Barbara

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
10
violations on file
0
still open
ViolationTypeStatusPeriod
MCL Health-based Resolved 2004-09-01 → 2004-09-30
MCL Health-based Resolved 2004-09-01 → 2004-09-30
MCL Health-based Resolved 2000-07-01 → 2000-07-31
MCL Health-based Resolved 2000-07-01 → 2000-07-31
MCL Health-based Resolved 1997-03-01 → 1997-03-31
MCL Health-based Resolved 1997-03-01 → 1997-03-31
MCL Health-based Resolved 1996-08-01 → 1996-08-31
MCL Health-based Resolved 1996-08-01 → 1996-08-31
MR Monitoring Archived 1981-10-01 → 1982-09-30
MR Monitoring Archived 1980-10-30 → 1981-10-29

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 single worst sample on record — over 100% is worth reading, but is not by itself a violation. Formal violations are listed separately.
ContaminantLevel vs EPA limitDetection rateSourcePeriod
Nitrate
6300 µg/L 63%
of the EPA limit 10000 µg/L
 50/70 SYR4 2012–2019
Fluoride
400 µg/L 10%
of the EPA limit 4000 µg/L
 9/11 SYR4 2012–2019
Nitrate-Nitrite
400000 µg/L 4000%
of the EPA limit, in the worst sample — 10000 µg/L
 6/10 SYR4 2012–2019
Combined Uranium
3.5313 µg/L 12%
of the EPA limit 30 µg/L
 5/6 SYR4 2013–2016
Barium
77.5 µg/L 3.9%
of the EPA limit 2000 µg/L
 4/10 SYR4 2012–2019
Chromium
6 µg/L 6%
of the EPA limit 100 µg/L
 4/10 SYR4 2012–2019
Lead
0.0 mg/L 0%
of the EPA limit 0.0150 mg/L
 4/4 LCR 2023
Lead
22.9 µg/L 153%
of the EPA limit, in the worst sample — 15 µg/L
 4/10 SYR4 2012–2019
Selenium
1 µg/L 2%
of the EPA limit 50 µg/L
 1/10 SYR4 2012–2019
34 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-Dichloroethane1,2-DichloropropaneAntimony, TotalArsenicBenzeneBeryllium, TotalBromodichloromethaneBromoformChlorobenzeneCopperCadmiumCarbon TetrachlorideChloroformDichloromethaneDibromochloromethaneEthylbenzeneMercuryNitriteStyreneTTHMTetrachloroethyleneThallium, TotalTolueneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact
SAN MARCOS, MWC
Phone
805-452-1487
Email
ops@sanmarcosmutualwater.com

Frequently asked questions about San Marcos Mutual Water Company

Is San Marcos Mutual Water Company tap water safe to drink?

EPA monitoring detected 9 contaminants in San Marcos 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 San Marcos Mutual Water Company's water?

EPA monitoring detected Nitrate, Fluoride, Nitrate-Nitrite, Combined Uranium, Barium, and others. The full list with the level and data source for each is above.

How many people does San Marcos Mutual Water Company serve?

San Marcos Mutual Water Company reports serving 120 people in California, per its EPA record.

Has San Marcos Mutual Water Company had any water quality violations?

The EPA has 10 violations on file for San Marcos Mutual Water Company, 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.