San Mateo, California Water Quality Report
Water quality data for 3 water systems serving 239 people.
Water Source
Detected Contaminants
No contaminant data available for this location.
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Compliance & Violations
Active Violations (32)
52
Jul 1, 2025
52
Jul 1, 2025
52
Oct 1, 2024
52
Oct 1, 2024
51
Jan 1, 1993
Violation
Unknown
Violation
Unknown
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Unknown
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Unknown
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Unknown
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Unknown
Violation
Unknown
Violation
Unknown
Violation
Unknown
Violation
Unknown
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Unknown
Violation
Unknown
Violation
Unknown
Violation
Unknown
Violation
Unknown
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Unknown
Violation
Unknown
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Unknown
Violation
Unknown
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Unknown
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Unknown
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Unknown
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Unknown
Violation
Unknown
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Unknown
Violation
Unknown
Violation
Unknown
Resolved Violations (299)
4G
Oct 17, 2024
2E
Oct 17, 2024
2E
Oct 17, 2024
2E
Oct 17, 2024
2E
Oct 17, 2024
+ 294 more resolved violations
Frequently Asked Questions
Is San Mateo tap water safe to drink?
San Mateo's water meets all EPA maximum contaminant levels. However, 0 contaminants were detected at various levels. Some residents may prefer additional filtration for peace of mind.
What contaminants are in San Mateo tap water?
0 contaminants have been detected in San Mateo's water supply across 3 water systems. See the full contaminant table above for details.
How can I improve my water quality in San Mateo?
Install a water filter rated for the specific contaminants found in San Mateo's water. See our filter recommendations above. You can also request your utility's Consumer Confidence Report for the most current test results.
Does San Mateo have any water quality violations?
Yes, San Mateo currently has 32 active violations. See the violations section above for details.