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Potrero, CA Tap Water Quality 2026

Water quality report for Potrero, CA — PFAS, lead and copper results, violation history and state inspection findings from EPA SDWIS.

A look at Potrero's drinking water using EPA enforcement records: violations, lead and copper results, PFAS sampling and state inspection findings.

Main Utility: Twin Lakes Resort PWSID: CA3701793 Updated: 2026 Q2
✅

No federal limits exceeded on record

Lead was not detected and no violations are open. PFAS has never been sampled at this system.

B

Potrero earns a B for water quality

Graded on violations and lead, with state inspection findings. PFAS not tested.

Lead: not detected
PFAS never sampled at this system
40 violations since 2015, 32 health-based
No violations currently open
Potrero's lead level vs. all California community water systems
0 ppb5 ppb10 ppb15 ppb
Lead level: Not detected — 0% of the federal action level
✓ Lower lead than % of California utilities
Population Served
424
~153 connections
Water Source
Groundwater
Drawn from wells — SDWIS source code GW
Active Violations
0
40 since 2015, all resolved

Lead & Copper Testing

Lead (Pb)
90th percentile of tap samples collected across the distribution system
0% of EPA action level
Not detected
Action level: 15 ppb
Lead was not detected at the 90th percentile — the result fell below the laboratory detection limit. That is not the same as an absence of lead in every tap, and older homes with lead service lines can still show higher readings.

Contaminant Violations (2015–Present)

ContaminantTypeMeasuredLimitPeriodStatus
Arsenic MCL EXCEEDANCE 11.7 UG/L 0.010 mg/L 2025 Archived
Arsenic MCL EXCEEDANCE 12 UG/L 0.010 mg/L 2025 Archived
Arsenic MCL EXCEEDANCE 11.7 UG/L 0.010 mg/L 2024 Archived
Arsenic MCL EXCEEDANCE 11.7 UG/L 0.010 mg/L 2024 Archived
Arsenic MONITORING AND REPORTING — 0.010 mg/L 2024 Archived
Arsenic MCL EXCEEDANCE 12 UG/L 0.010 mg/L 2024 Archived
Arsenic MCL EXCEEDANCE 12 UG/L 0.010 mg/L 2024 Archived
Arsenic MCL EXCEEDANCE 12 UG/L 0.010 mg/L 2023 Archived
Arsenic MCL EXCEEDANCE 12 UG/L 0.010 mg/L 2023 Archived
Arsenic MONITORING AND REPORTING — 0.010 mg/L 2023 Archived
Arsenic MCL EXCEEDANCE 12 UG/L 0.010 mg/L 2023 Archived
Nitrate MONITORING AND REPORTING — 10 mg/L 2023 Archived
Arsenic MCL EXCEEDANCE 12 UG/L 0.010 mg/L 2022 Archived
Arsenic MCL EXCEEDANCE 12.5 UG/L 0.010 mg/L 2022 Archived
Arsenic MCL EXCEEDANCE 12 UG/L 0.010 mg/L 2022 Archived
Arsenic MCL EXCEEDANCE 11.2 UG/L 0.010 mg/L 2022 Archived
Lead and Copper Rule MONITORING AND REPORTING — TT 2021 Addressed
Arsenic MCL EXCEEDANCE 12.2 UG/L 0.010 mg/L 2021 Archived
Arsenic MCL EXCEEDANCE 11.6 UG/L 0.010 mg/L 2021 Archived
Arsenic MCL EXCEEDANCE 11.8 UG/L 0.010 mg/L 2021 Archived
Arsenic MCL EXCEEDANCE 11.6 UG/L 0.010 mg/L 2020 Archived
Arsenic MCL EXCEEDANCE 11.4 UG/L 0.010 mg/L 2020 Archived
Arsenic MCL EXCEEDANCE 11.3 UG/L 0.010 mg/L 2020 Archived
Arsenic MONITORING AND REPORTING — 0.010 mg/L 2019 Archived
Arsenic MCL EXCEEDANCE 11.02 UG/L 0.010 mg/L 2019 Archived
Arsenic MCL EXCEEDANCE 11 UG/L 0.010 mg/L 2019 Archived
Arsenic MCL EXCEEDANCE 11.2 UG/L 0.010 mg/L 2019 Archived
Arsenic MCL EXCEEDANCE 11.3 UG/L 0.010 mg/L 2018 Archived
Arsenic MCL EXCEEDANCE 12 MG/L 0.010 mg/L 2018 Archived
Arsenic MCL EXCEEDANCE 12 MG/L 0.010 mg/L 2018 Archived
Arsenic MCL EXCEEDANCE 12 MG/L 0.010 mg/L 2017 Archived
Arsenic MCL EXCEEDANCE 11.75 MG/L 0.010 mg/L 2017 Archived
Arsenic MCL EXCEEDANCE 0.012 MG/L 0.010 mg/L 2017 Archived
Arsenic MONITORING AND REPORTING — 0.010 mg/L 2017 Archived
Arsenic MCL EXCEEDANCE 0.0115 MG/L 0.010 mg/L 2017 Archived
Public Notice OTHER — — 2016 Addressed
Arsenic MCL EXCEEDANCE 0.0115 MG/L 0.010 mg/L 2016 Archived
Arsenic MCL EXCEEDANCE 0.0114 MG/L 0.010 mg/L 2016 Archived
Arsenic MCL EXCEEDANCE 0.0116 MG/L 0.010 mg/L 2016 Archived
Coliform (TCR) MONITORING AND REPORTING — 5% of samples 2015 Resolved
Understanding violation types MCL violations mean a contaminant exceeded the federal maximum limit — the most serious type.
TT (Treatment Technique) violations mean required treatment procedures weren't followed, but don't necessarily mean contamination occurred.

Violation History

40 violations are on record since 2015, of which 32 were health-based. All have been resolved and none remain open.

About the Main Water System

Utility Twin Lakes Resort
PWSID CA3701793
Water source Groundwater — Drawn from wells — SDWIS source code GW
Population served 424
Service connections 153
Systems serving this area 1
Regulator State primacy agency
Data through 2026 Q2 — EPA SDWIS

Frequently Asked Questions

Is Potrero tap water safe to drink? ▼
No federal limit is exceeded on record. No violations are currently open.
Does Potrero water have PFAS? ▼
This system has never been sampled for PFAS. EPA's national monitoring covered systems serving 3,300 people or more, so no results exist — which is not evidence that none is present.
Who supplies water to Potrero? ▼
Twin Lakes Resort (PWSID CA3701793). Groundwater. Drawn from wells — SDWIS source code GW
When was this system last inspected? ▼
It was last inspected on 2026-01-28. No significant deficiencies were recorded.

What Should Potrero Residents Do?

1
Read your annual water report
Your supplier publishes a Consumer Confidence Report each July covering the prior year.
2
Check for a lead service line
Lead reaches tap water mainly through service lines and household plumbing. Suppliers now publish an inventory identifying lead lines.
3
Flush before drinking
If water has sat in pipes more than six hours, run the cold tap for two minutes before drinking or cooking.

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