Is Coastside County Water District Tap Water Safe? Quality Report

Water source: Surface water
Ownership: Local government
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	2008-04-01 → 2008-04-30
TT	Health-based	Resolved	2008-04-01 → 2008-04-30
TT	Health-based	Resolved	2005-06-01 → 2005-06-30
TT	Health-based	Resolved	2005-06-01 → 2005-06-30
MCL	Health-based	Resolved	2004-01-01 → 2004-01-31
MCL	Health-based	Resolved	2004-01-01 → 2004-01-31
MCL	Health-based	Resolved	2002-01-01 → 2002-01-31
MCL	Health-based	Resolved	2002-01-01 → 2002-01-31
MCL	Health-based	Resolved	2002-01-01 → 2002-01-31
MCL	Health-based	Resolved	2002-01-01 → 2002-01-31

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.

Contaminant	Level vs EPA limit	Detection rate	Source	Period
Fluoride	1000 µg/L 25% of the EPA limit 4000 µg/L	214/221	SYR4	2012–2019
Nitrate	5424 µg/L 54% of the EPA limit 10000 µg/L	156/256	SYR4	2012–2019
TTHM	130 µg/L 163% of the EPA limit, in the worst sample — 80 µg/L	116/120	SYR4	2012–2019
Chloroform	52 µg/L No EPA limit set	111/120	SYR4	2012–2019
Bromodichloromethane	41 µg/L No EPA limit set	109/120	SYR4	2012–2019
Dibromochloromethane	41 µg/L No EPA limit set	98/120	SYR4	2012–2019
Dichloroacetic Acid	19 µg/L No EPA limit set	98/100	SYR4	2013–2019
Total Haloacetic Acids (HAA5)	62 µg/L 103% of the EPA limit, in the worst sample — 60 µg/L	98/100	SYR4	2013–2019
Trichloroacetic Acid	37 µg/L No EPA limit set	98/100	SYR4	2013–2019
Dibromoacetic Acid	11 µg/L No EPA limit set	68/100	SYR4	2013–2019
Bromoform	13 µg/L No EPA limit set	67/120	SYR4	2012–2019
Chromium	18 µg/L 18% of the EPA limit 100 µg/L	54/297	SYR4	2012–2019
Lead	0.0016 mg/L 11% of the EPA limit 0.0150 mg/L	33/33	LCR	2024
Copper	24 µg/L 1.8% of the EPA limit 1300 µg/L	23/363	SYR4	2012–2019
Monochloroacetic Acid	2.9 µg/L No EPA limit set	9/100	SYR4	2013–2019
Barium	33 µg/L 1.7% of the EPA limit 2000 µg/L	8/64	SYR4	2012–2019
Monobromoacetic Acid	1.2 µg/L No EPA limit set	4/100	SYR4	2013–2019
Arsenic	8 µg/L 80% of the EPA limit 10 µg/L	1/65	SYR4	2012–2019
Di(2-ethylhexyl) Phthalate	3.2 µg/L 53% of the EPA limit 6 µg/L	1/57	SYR4	2012–2019

90 contaminants tested, none detected

1,1,1-Trichloroethane1,1,2-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, TotalAsbestosAtrazineBhc-GammaBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCyanideCadmiumCarbofuranCarbon TetrachlorideChlordaneDichloromethaneDalaponDi(2-ethylhexyl) AdipateDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoLeadMercuryMethoxychlorNetfosaaNfdhaNmefosaaNitriteOxamylPfbaPFBSPfdaPfdoaPfeesaPfhpaPfhpsPfhxaPFHXSPfmbaPfmpaPFNAPFOAPFOSPfpeaPfpesPftaPftrdaPfunaPentachlorophenolPicloramSeleniumSimazineStyreneTetrachloroethyleneThallium, TotalTolueneTotal Polychlorinated Biphenyls (PCB)ToxapheneTrichloroethyleneVinyl ChlorideXylenes, Totalcis-1,2-DichloroethyleneLithiumO-DichlorobenzeneP-Dichlorobenzenetrans-1,2-Dichloroethylene

Utility contact

Contact: ROGREN, MARY
Phone: 650-276-0889
Email: mrogren@coastsidewater.org

Frequently asked questions about Coastside County Water District

Is Coastside County Water District tap water safe to drink?

EPA monitoring detected 19 contaminants in Coastside County Water District'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 Coastside County Water District's water?

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

How many people does Coastside County Water District serve?

Coastside County Water District reports serving 18,940 people in California, per its EPA record.

Has Coastside County Water District had any water quality violations?

The EPA has 32 violations on file for Coastside County Water District, of which 14 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.