Is Montara Water and Sanitary 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
MCL	Health-based	Resolved	2010-06-01 → 2010-06-30
MCL	Health-based	Resolved	2010-06-01 → 2010-06-30
MCL	Health-based	Resolved	1996-12-31 → 1997-12-01
MCL	Health-based	Resolved	1996-12-31 → 1997-12-01
MCL	Health-based	Resolved	1996-02-01 → 1996-02-29
MR	Monitoring	Resolved	1996-12-31 → 1997-12-01
MR	Monitoring	Resolved	1996-12-31 → 1997-12-01

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.

Contaminant	Level vs EPA limit	Detection rate	Source	Period
Nitrate	9944 µg/L 99% of the EPA limit 10000 µg/L worst single sample: 11752 µg/L	510/944	SYR4	2012–2019
Fluoride	1700 µg/L 43% of the EPA limit 4000 µg/L worst single sample: 2600 µg/L	100/104	SYR4	2012–2019
cis-1,2-Dichloroethylene	5 µg/L 7.1% of the EPA limit 70 µg/L worst single sample: 8.3 µg/L	61/185	SYR4	2012–2019
Trichloroethylene	3.095 µg/L 62% of the EPA limit 5 µg/L worst single sample: 3.6 µg/L	42/185	SYR4	2012–2019
Arsenic	7.7 µg/L 77% of the EPA limit 10 µg/L worst single sample: 8 µg/L	37/58	SYR4	2012–2019
trans-1,2-Dichloroethylene	1.74 µg/L 1.7% of the EPA limit 100 µg/L worst single sample: 2.1 µg/L	33/183	SYR4	2012–2019
Bromoform	36.9 µg/L No EPA limit set worst single sample: 39 µg/L	23/39	SYR4	2014–2019
Dibromochloromethane	12.9 µg/L No EPA limit set worst single sample: 14 µg/L	23/39	SYR4	2014–2019
TTHM	51.3 µg/L 64% of the EPA limit 80 µg/L worst single sample: 54 µg/L	23/39	SYR4	2014–2019
Dibromoacetic Acid	7.49 µg/L No EPA limit set worst single sample: 7.9 µg/L	22/22	SYR4	2014–2019
Total Haloacetic Acids (HAA5)	7.88 µg/L 13% of the EPA limit 60 µg/L worst single sample: 9.7 µg/L	22/22	SYR4	2014–2019
Bromodichloromethane	4.1 µg/L No EPA limit set worst single sample: 5.7 µg/L	21/39	SYR4	2014–2019
Lead	0.0 mg/L 0% of the EPA limit 0.0150 mg/L	21/21	LCR	2023
Chloroform	5.28 µg/L No EPA limit set worst single sample: 6.8 µg/L	9/39	SYR4	2014–2019
Dichloroacetic Acid	1.75 µg/L No EPA limit set worst single sample: 1.9 µg/L	7/22	SYR4	2014–2019
Nitrate-Nitrite	9375 µg/L 94% of the EPA limit 10000 µg/L worst single sample: 10000 µg/L	6/14	SYR4	2017–2019
Trichloroacetic Acid	3.575 µg/L No EPA limit set worst single sample: 4.2 µg/L	6/22	SYR4	2014–2019
Chromium	22.95 µg/L 23% of the EPA limit 100 µg/L worst single sample: 24 µg/L	4/40	SYR4	2012–2019
Toluene	120.035 µg/L 12% of the EPA limit 1000 µg/L worst single sample: 140 µg/L	4/185	SYR4	2012–2019
1,2-Dichloropropane	0.5880 µg/L 12% of the EPA limit 5 µg/L worst single sample: 0.5900 µg/L	2/185	SYR4	2012–2019
Selenium	8.345 µg/L 17% of the EPA limit 50 µg/L worst single sample: 8.5 µg/L	2/35	SYR4	2012–2019
Carbon Tetrachloride	1.1 µg/L 22% of the EPA limit 5 µg/L	1/185	SYR4	2012–2019
Xylenes, Total	0.5200 µg/L 0% of the EPA limit 10000 µg/L	1/186	SYR4	2012–2019

87 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-PF3ONSAdonaAntimony, TotalAsbestosAtrazineBhc-GammaBariumBenzeneBenzo(A)PyreneBeryllium, TotalChlorobenzeneCopperCyanideCadmiumCarbofuranChlordaneDichloromethaneDalaponDi(2-ethylhexyl) AdipateDi(2-ethylhexyl) PhthalateDinosebDiquatEthylene DibromideEndothallEndrinEthylbenzeneGlyphosateHexachlorobenzeneHfpo-DaHeptachlorHeptachlor EpoxideHexachlorocyclopentadieneLassoLeadMercuryMethoxychlorMonobromoacetic AcidMonochloroacetic AcidNetfosaaNfdhaNmefosaaNitriteOxamylPfbaPFBSPfdaPfdoaPfeesaPfhpaPfhpsPfhxaPFHXSPfmbaPfmpaPFNAPFOAPFOSPfpeaPfpesPftaPftrdaPfunaPentachlorophenolPicloramSimazineStyreneTetrachloroethyleneThallium, TotalTotal Polychlorinated Biphenyls (PCB)ToxapheneVinyl ChlorideLithiumO-DichlorobenzeneP-Dichlorobenzene

Utility contact

Contact: HELDMAIER, CLEMENS
Phone: 650-728-3358
Email: clemens@mwsd.net

Frequently asked questions about Montara Water and Sanitary District

Is Montara Water and Sanitary District tap water safe to drink?

EPA monitoring detected 23 contaminants in Montara Water and Sanitary 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 Montara Water and Sanitary District's water?

EPA monitoring detected Nitrate, Fluoride, cis-1,2-Dichloroethylene, Trichloroethylene, Arsenic, and others. The full list with the level and data source for each is above.

How many people does Montara Water and Sanitary District serve?

Montara Water and Sanitary District reports serving 6,078 people in California, per its EPA record.

Has Montara Water and Sanitary District had any water quality violations?

The EPA has 7 violations on file for Montara Water and Sanitary District, of which 5 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.