Is California Water Service-S San Francisco Tap Water Safe? Quality Report

Water source: SWP
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.

health-based violations

violations on file

still open

Violation	Type	Status	Period
TT	Health-based	Resolved	1993-06-01 → 1993-06-30
TT	Health-based	Resolved	1993-06-01 → 1993-06-30
MCL	Health-based	Resolved	1992-10-01 → 1992-10-31
MR	Monitoring	Resolved	2013-06-01
MR	Monitoring	Resolved	2013-06-01

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 single worst sample on record — over 100% is worth reading, but is not by itself a violation. Formal violations are listed separately.

Contaminant	Level vs EPA limit	Detection rate	Source	Period
Nitrate	8606 µg/L 86% of the EPA limit 10000 µg/L	1060/1148	SYR4	2012–2019
TTHM	100 µg/L 125% of the EPA limit, in the worst sample — 80 µg/L	364/418	SYR4	2012–2019
Bromodichloromethane	18 µg/L No EPA limit set	348/418	SYR4	2012–2019
Chloroform	77 µg/L No EPA limit set	327/418	SYR4	2012–2019
Total Haloacetic Acids (HAA5)	56 µg/L 93% of the EPA limit 60 µg/L	264/265	SYR4	2012–2019
Dichloroacetic Acid	34 µg/L No EPA limit set	263/266	SYR4	2012–2019
Trichloroacetic Acid	24 µg/L No EPA limit set	263/266	SYR4	2012–2019
Dibromochloromethane	5.3 µg/L No EPA limit set	249/418	SYR4	2012–2019
Arsenic	16.211 µg/L 162% of the EPA limit, in the worst sample — 10 µg/L	204/263	SYR4	2012–2019
Bromoform	5.67 µg/L No EPA limit set	189/418	SYR4	2012–2019
Dibromoacetic Acid	3.4 µg/L No EPA limit set	80/266	SYR4	2012–2019
Chromium	21 µg/L 21% of the EPA limit 100 µg/L	48/92	SYR4	2012–2019
Copper	73.33 µg/L 5.6% of the EPA limit 1300 µg/L	44/163	SYR4	2012–2019
Combined Uranium	2.57472 µg/L 8.6% of the EPA limit 30 µg/L	36/77	SYR4	2012–2019
Antimony, Total	0.1320 µg/L 2.2% of the EPA limit 6 µg/L	29/89	SYR4	2012–2019
1,2-Dichloropropane	1.04 µg/L 21% of the EPA limit 5 µg/L	27/373	SYR4	2012–2019
Lead	5.359 µg/L 36% of the EPA limit 15 µg/L	27/89	SYR4	2012–2019
Monochloroacetic Acid	3.1 µg/L No EPA limit set	27/266	SYR4	2012–2019
Lead	0.0041 mg/L 27% of the EPA limit 0.0150 mg/L	26/26	LCR	2025
Barium	190 µg/L 9.5% of the EPA limit 2000 µg/L	21/39	SYR4	2012–2019
Selenium	2.23 µg/L 4.5% of the EPA limit 50 µg/L	20/83	SYR4	2012–2019
Cadmium	0.0270 µg/L 0.5% of the EPA limit 5 µg/L	16/88	SYR4	2012–2019
Beryllium, Total	0.0100 µg/L 0.3% of the EPA limit 4 µg/L	12/85	SYR4	2012–2019
Nitrate-Nitrite	7400 µg/L 74% of the EPA limit 10000 µg/L	4/7	SYR4	2017–2019
Fluoride	140 µg/L 3.5% of the EPA limit 4000 µg/L	3/21	SYR4	2012–2019
Trichloroethylene	0.7500 µg/L 15% of the EPA limit 5 µg/L	3/373	SYR4	2012–2019
Thallium, Total	0.0230 µg/L 1.2% of the EPA limit 2 µg/L	2/86	SYR4	2012–2019
Lithium	23.6 µg/L No EPA limit set	2/6	UCMR-5	2025
Mercury	0.0130 µg/L 0.7% of the EPA limit 2 µg/L	1/23	SYR4	2012–2019
Monobromoacetic Acid	1.2 µg/L No EPA limit set	1/266	SYR4	2012–2019

83 contaminants tested, none detected

1,1,1-Trichloroethane1,1,2-Trichloroethane1,1-Dichloroethylene1,2,4-Trichlorobenzene1,2-DIBROMO-3-CHLOROPROPANE1,2-Dichloroethane11Cl-PF3OUdS2,3,7,8-TCDD2,4,5-TP2,4-D4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaAsbestosAtrazineBhc-GammaBenzeneBenzo(A)PyreneBromateChlorobenzeneCyanideCarbofuranCarbon TetrachlorideChlordaneDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateGross Beta Particle ActivityHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoMethoxychlorNetfosaaNfdhaNmefosaaNitriteOxamylPfbaPFBSPfdaPfdoaPfeesaPfhpaPfhpsPfhxaPFHXSPfmbaPfmpaPFNAPFOAPFOSPfpeaPfpesPftaPftrdaPfunaPentachlorophenolPicloramSimazineStyreneTetrachloroethyleneTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact: JAMES, SOPHIE
Phone: 408-367-8593
Email: sjames@calwater.com

Frequently asked questions about California Water Service-S San Francisco

Is California Water Service-S San Francisco tap water safe to drink?

EPA monitoring detected 30 contaminants in California Water Service-S San Francisco'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 California Water Service-S San Francisco's water?

EPA monitoring detected Nitrate, TTHM, Bromodichloromethane, Chloroform, Total Haloacetic Acids (HAA5), and others. The full list with the level and data source for each is above.

How many people does California Water Service-S San Francisco serve?

California Water Service-S San Francisco reports serving 64,146 people in California, per its EPA record.

Has California Water Service-S San Francisco had any water quality violations?

The EPA has 5 violations on file for California Water Service-S San Francisco, of which 3 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.