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Tap water quality report

Mid-Peninsula Water District

EPA monitoring tested this supplier for 42 contaminants and detected 9. A detection doesn't automatically mean the water is unsafe — the level and EPA source for each is below.

42
contaminants tested
9
detected
30,609
people served
6
health-based violations
California rankingsLead in CaliforniaPFAS in California
Water source
SWP
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.

6
health-based violations
6
violations on file
0
still open
ViolationTypeStatusPeriod
TT Health-based Resolved 2015-03-01 → 2015-03-31
TT Health-based Resolved 2015-03-01 → 2015-03-31
MCL Health-based Resolved 2002-12-01 → 2002-12-31
MCL Health-based Resolved 2002-12-01 → 2002-12-31
MCL Health-based Resolved 2001-12-01 → 2001-12-31
MCL Health-based Resolved 2001-12-01 → 2001-12-31

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 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
Chloroform
60.605 µg/L
No EPA limit set
worst single sample: 71 µg/L
120/120 SYR4 2012–2019
Dichloroacetic Acid
26.62 µg/L
No EPA limit set
worst single sample: 28.9 µg/L
120/120 SYR4 2012–2019
TTHM
63.38 µg/L 79%
of the EPA limit 80 µg/L
worst single sample: 73.3 µg/L
120/120 SYR4 2012–2019
Total Haloacetic Acids (HAA5)
48.725 µg/L 81%
of the EPA limit 60 µg/L
worst single sample: 58.4 µg/L
120/120 SYR4 2012–2019
Trichloroacetic Acid
22.35 µg/L
No EPA limit set
worst single sample: 30.4 µg/L
120/120 SYR4 2012–2019
Bromodichloromethane
5.003 µg/L
No EPA limit set
worst single sample: 6.9 µg/L
98/120 SYR4 2012–2019
Lead
0.0 mg/L 0%
of the EPA limit 0.0150 mg/L
 48/48 LCR 2024
Monochloroacetic Acid
2.87 µg/L
No EPA limit set
worst single sample: 2.9 µg/L
27/120 SYR4 2012–2019
Dibromochloromethane
1.314 µg/L
No EPA limit set
worst single sample: 1.32 µg/L
13/120 SYR4 2012–2019
33 contaminants tested, none detected
11Cl-PF3OUdS4:2 Fts6:2 Fts8:2 Fts9Cl-PF3ONSAdonaBromoformDibromoacetic AcidHfpo-DaMonobromoacetic AcidNetfosaaNfdhaNmefosaaPfbaPFBSPfdaPfdoaPfeesaPfhpaPfhpsPfhxaPFHXSPfmbaPfmpaPFNAPFOAPFOSPfpeaPfpesPftaPftrdaPfunaLithium

Utility contact

Contact
WUELFING, KAT
Phone
650-591-8941
Email
[email protected]

Frequently asked questions about Mid-Peninsula Water District

Is Mid-Peninsula Water District tap water safe to drink?

EPA monitoring detected 9 contaminants in Mid-Peninsula 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 Mid-Peninsula Water District's water?

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

How many people does Mid-Peninsula Water District serve?

Mid-Peninsula Water District reports serving 30,609 people in California, per its EPA record.

Has Mid-Peninsula Water District had any water quality violations?

The EPA has 6 violations on file for Mid-Peninsula Water District, 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.