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Tap water quality report

Oku Incorporated

EPA monitoring tested this supplier for 80 contaminants and detected 21. A detection doesn't automatically mean the water is unsafe — the level and EPA source for each is below.

80
contaminants tested
21
detected
35
people served
9
health-based violations
California rankingsLead in CaliforniaPFAS in California
Water source
Ground water
Ownership
Private
Counties served
San Mateo

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.

9
health-based violations
94
violations on file
3
still open
ViolationTypeStatusPeriod
MCL Health-based Resolved 2011-07-01 → 2011-09-30
MCL Health-based Resolved 2011-07-01 → 2011-09-30
MCL Health-based Resolved 2011-07-01 → 2011-09-30
MCL Health-based Resolved 2011-07-01 → 2011-09-30
TT Health-based Resolved 2010-10-01 → 2010-10-31
TT Health-based Resolved 2010-10-01 → 2010-10-31
TT Health-based Resolved 2010-10-01 → 2010-10-31
TT Health-based Resolved 1996-02-01 → 1996-02-29
TT Health-based Resolved 1996-02-01 → 1996-02-29
MR Monitoring Addressed 2025-10-01

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
Bromodichloromethane
35.2 µg/L
No EPA limit set
worst single sample: 43 µg/L
13/17 SYR4 2012–2019
Chloroform
66.6 µg/L
No EPA limit set
worst single sample: 81 µg/L
13/17 SYR4 2012–2019
TTHM
108 µg/L 135%
of the EPA limit, at the 95th percentile of samples — 80 µg/L
worst single sample: 120 µg/L
13/15 SYR4 2012–2019
Dibromochloromethane
18.35 µg/L
No EPA limit set
worst single sample: 20 µg/L
12/17 SYR4 2012–2019
Bromoform
3.64 µg/L
No EPA limit set
worst single sample: 4.2 µg/L
9/17 SYR4 2012–2019
Dichloroacetic Acid
41.2 µg/L
No EPA limit set
worst single sample: 42 µg/L
9/17 SYR4 2012–2019
Total Haloacetic Acids (HAA5)
157.64 µg/L 263%
of the EPA limit, at the 95th percentile of samples — 60 µg/L
worst single sample: 197 µg/L
9/16 SYR4 2012–2019
Trichloroacetic Acid
77.65 µg/L
No EPA limit set
worst single sample: 99 µg/L
8/17 SYR4 2012–2019
Lead
0.0 mg/L 0%
of the EPA limit 0.0150 mg/L
 7/7 LCR 2022
Dibromoacetic Acid
4.925 µg/L
No EPA limit set
worst single sample: 5.4 µg/L
6/17 SYR4 2012–2019
Monobromoacetic Acid
14 µg/L
No EPA limit set
worst single sample: 15 µg/L
6/17 SYR4 2012–2019
Monochloroacetic Acid
42 µg/L
No EPA limit set
worst single sample: 45 µg/L
5/17 SYR4 2012–2019
Fluoride
506.5 µg/L 13%
of the EPA limit 4000 µg/L
worst single sample: 520 µg/L
4/4 SYR4 2012–2018
Nitrate
497.2 µg/L 5%
of the EPA limit 10000 µg/L
 4/18 SYR4 2012–2019
Arsenic
4.1 µg/L 41%
of the EPA limit 10 µg/L
 3/4 SYR4 2012–2018
Barium
34.95 µg/L 1.7%
of the EPA limit 2000 µg/L
worst single sample: 35 µg/L
2/4 SYR4 2012–2018
Copper
142.785 µg/L 11%
of the EPA limit 1300 µg/L
worst single sample: 150 µg/L
2/4 SYR4 2012–2018
Cyanide
2.16 µg/L 1.1%
of the EPA limit 200 µg/L
worst single sample: 2.2 µg/L
2/3 SYR4 2013–2018
Combined Uranium
0.5587 µg/L 1.9%
of the EPA limit 30 µg/L
 1/1 SYR4 2013
Gross Beta Particle Activity
6.54 pCi/L
No EPA limit set
 1/1 SYR4 2015
Selenium
9.8 µg/L 20%
of the EPA limit 50 µg/L
 1/4 SYR4 2012–2018
59 contaminants tested, none detected
1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane1,2-Dichloropropane2,4,5-TP2,4-DAntimony, TotalAtrazineBhc-GammaBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCadmiumCarbofuranCarbon TetrachlorideChlordaneChromiumDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateHexachlorobenzeneHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoLeadMercuryMethoxychlorNitrate-NitriteNitriteOxamylPentachlorophenolPicloramSimazineStyreneTetrachloroethyleneThallium, TotalTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact
OKU, JAMES
Phone
650-245-3088
Email
[email protected]

Frequently asked questions about Oku Incorporated

Is Oku Incorporated tap water safe to drink?

EPA monitoring detected 21 contaminants in Oku Incorporated'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 Oku Incorporated's water?

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

How many people does Oku Incorporated serve?

Oku Incorporated reports serving 35 people in California, per its EPA record.

Has Oku Incorporated had any water quality violations?

The EPA has 94 violations on file for Oku Incorporated, of which 9 are health-based (a contaminant limit or required treatment was breached) and 3 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.