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Great Oaks Wc Inc

EPA monitoring tested this supplier for 112 contaminants and detected 20. A detection doesn't automatically mean the water is unsafe — the level and EPA source for each is below.

112
contaminants tested
20
detected
110,088
people served
6
health-based violations
California rankingsLead in CaliforniaPFAS in California
Water source
Ground water
Ownership
Private
Counties served
Santa Clara

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.

6
health-based violations
10
violations on file
0
still open
ViolationTypeStatusPeriod
MCL Health-based Resolved 2015-03-01 → 2015-03-31
MCL Health-based Resolved 2015-03-01 → 2015-03-31
MCL Health-based Resolved 2013-09-01 → 2013-09-30
MCL Health-based Resolved 2013-09-01 → 2013-09-30
MCL Health-based Resolved 1992-09-01 → 1992-09-30
MCL Health-based Resolved 1992-09-01 → 1992-09-30
MR Monitoring Resolved 2005-08-01 → 2005-08-31
MR Monitoring Resolved 2005-08-01 → 2005-08-31
MR Monitoring Resolved 2002-01-01
MR Monitoring Resolved 2002-01-01

PFAS detected

PFAS are industrial “forever chemicals”. These are the EPA's latest nationwide test results (2023–2025).
ContaminantMaxDetection ratePeriod
Pfhxa 0.0045 µg/L 5/37 2025
PFHXS 0.0080 µg/L 5/37 2025
Pfpea 0.0047 µg/L 5/37 2025
PFOS 0.0046 µg/L 1/37 2025

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
Nitrate
6555 µg/L 66%
of the EPA limit 10000 µg/L
worst single sample: 7600 µg/L
310/310 SYR4 2012–2019
Fluoride
224.5 µg/L 5.6%
of the EPA limit 4000 µg/L
worst single sample: 260 µg/L
52/52 SYR4 2013–2019
Nitrate-Nitrite
838000 µg/L 8380%
of the EPA limit, at the 95th percentile of samples — 10000 µg/L
worst single sample: 1000000 µg/L
49/49 SYR4 2013–2019
Barium
170 µg/L 8.5%
of the EPA limit 2000 µg/L
worst single sample: 180 µg/L
37/53 SYR4 2013–2019
Lithium
16 µg/L
No EPA limit set
 34/38 UCMR-5 2025
Lead
0.0 mg/L 0%
of the EPA limit 0.0150 mg/L
 31/31 LCR 2023
1,1,1-Trichloroethane
1.55 µg/L 0.8%
of the EPA limit 200 µg/L
worst single sample: 1.7 µg/L
16/69 SYR4 2012–2019
Bromoform
8.64 µg/L
No EPA limit set
worst single sample: 8.8 µg/L
5/12 SYR4 2013–2019
TTHM
12.6 µg/L 16%
of the EPA limit 80 µg/L
worst single sample: 13 µg/L
5/12 SYR4 2013–2019
Dibromoacetic Acid
2.085 µg/L
No EPA limit set
worst single sample: 2.1 µg/L
4/5 SYR4 2016–2019
Dibromochloromethane
4.04 µg/L
No EPA limit set
worst single sample: 4.1 µg/L
4/12 SYR4 2013–2019
Total Haloacetic Acids (HAA5)
2.095 µg/L 3.5%
of the EPA limit 60 µg/L
worst single sample: 2.1 µg/L
2/5 SYR4 2016–2019
Asbestos
0.1900 MFL 2.7%
of the EPA limit 7 MFL
 1/22 SYR4 2014–2019
Bromodichloromethane
1.1 µg/L
No EPA limit set
 1/12 SYR4 2013–2019
Gross Beta Particle Activity
4.7 pCi/L
No EPA limit set
 1/2 SYR4 2016
Mercury
1.9 µg/L 95%
of the EPA limit 2 µg/L
 1/52 SYR4 2013–2019
92 contaminants tested, none detected
1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-Dichloropropane11Cl-PF3OUdS2,3,7,8-TCDD2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAntimony, TotalArsenicAtrazineBhc-GammaBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCopperCyanideCadmiumCarbofuranCarbon TetrachlorideChlordaneChloroformChromiumCombined UraniumDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDichloroacetic AcidDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoLeadMethoxychlorMonobromoacetic AcidMonochloroacetic AcidNetfosaaNfdhaNmefosaaNitriteOxamylPfbaPFBSPfdaPfdoaPfeesaPfhpaPfhpsPfmbaPfmpaPFNAPFOAPfpesPftaPftrdaPfunaPentachlorophenolPicloramSeleniumSimazineStyreneTetrachloroethyleneThallium, TotalTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneTrichloroacetic AcidTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact
ROEDER, JOHN
Phone
408-227-9540
Email
[email protected]

Frequently asked questions about Great Oaks Wc Inc

Is Great Oaks Wc Inc tap water safe to drink?

EPA monitoring detected 20 contaminants in Great Oaks Wc Inc'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 Great Oaks Wc Inc's water?

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

How many people does Great Oaks Wc Inc serve?

Great Oaks Wc Inc reports serving 110,088 people in California, per its EPA record.

Has Great Oaks Wc Inc had any water quality violations?

The EPA has 10 violations on file for Great Oaks Wc Inc, of which 6 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.