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Tap water quality report

San Joaquin County - Thornton

EPA monitoring tested this supplier for 52 contaminants and detected 16. A detection doesn't automatically mean the water is unsafe — the level and EPA source for each is below.

52
contaminants tested
16
detected
964
people served
0
health-based violations
California rankingsLead in CaliforniaPFAS in California
Water source
Ground water
Ownership
Local government
Counties served
San Joaquin

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.

0
health-based violations
7
violations on file
0
still open
ViolationTypeStatusPeriod
MR Monitoring Resolved 2009-07-01 → 2009-07-31
MR Monitoring Resolved 2009-07-01 → 2009-07-31
MR Monitoring Resolved 2004-01-01 → 2004-01-31
MR Monitoring Resolved 2004-01-01 → 2004-01-31
MR Monitoring Resolved 1994-01-01 → 1994-01-31
MR Monitoring Resolved 1994-01-01 → 1994-01-31
Other Monitoring Archived 1985-08-01 → 1985-08-31

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 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
Lead
0.0 mg/L 0%
of the EPA limit 0.0150 mg/L
 14/14 LCR 2024
Bromodichloromethane
4 µg/L
No EPA limit set
 12/12 SYR4 2014–2019
Bromoform
9 µg/L
No EPA limit set
 12/12 SYR4 2014–2019
Dibromochloromethane
9 µg/L
No EPA limit set
 12/12 SYR4 2014–2019
TTHM
23 µg/L 29%
of the EPA limit 80 µg/L
 12/12 SYR4 2014–2019
Dibromoacetic Acid
3 µg/L
No EPA limit set
 11/12 SYR4 2014–2019
Total Haloacetic Acids (HAA5)
4 µg/L 6.7%
of the EPA limit 60 µg/L
 11/12 SYR4 2014–2019
Chloroform
1.4 µg/L
No EPA limit set
 7/12 SYR4 2014–2019
Barium
120 µg/L 6%
of the EPA limit 2000 µg/L
 5/6 SYR4 2013–2019
Nitrate
90.4 µg/L 0.9%
of the EPA limit 10000 µg/L
 4/32 SYR4 2012–2019
Arsenic
9 µg/L 90%
of the EPA limit 10 µg/L
 3/6 SYR4 2013–2019
Monobromoacetic Acid
2 µg/L
No EPA limit set
 3/12 SYR4 2014–2019
Chromium
2 µg/L 2%
of the EPA limit 100 µg/L
 2/6 SYR4 2013–2019
Fluoride
100 µg/L 2.5%
of the EPA limit 4000 µg/L
 2/6 SYR4 2013–2019
Mercury
0.0300 µg/L 1.5%
of the EPA limit 2 µg/L
 2/6 SYR4 2013–2019
Lead
1.5 µg/L 10%
of the EPA limit 15 µg/L
 1/6 SYR4 2013–2019
36 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-DichloropropaneAntimony, TotalAtrazineBenzeneBeryllium, TotalChlorobenzeneCopperCadmiumCarbon TetrachlorideDichloromethaneDichloroacetic AcidEthylene DibromideEthylbenzeneMonochloroacetic AcidNitrate-NitriteNitriteSeleniumSimazineStyreneTetrachloroethyleneThallium, TotalTolueneTrichloroacetic AcidTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact
IRONS, CLINTON
Phone
209-468-3090
Email
cirons@sjgov.org

Frequently asked questions about San Joaquin County - Thornton

Is San Joaquin County - Thornton tap water safe to drink?

EPA monitoring detected 16 contaminants in San Joaquin County - Thornton'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 Joaquin County - Thornton's water?

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

How many people does San Joaquin County - Thornton serve?

San Joaquin County - Thornton reports serving 964 people in California, per its EPA record.

Has San Joaquin County - Thornton had any water quality violations?

The EPA has 7 violations on file for San Joaquin County - Thornton, of which 0 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.