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Lake Oswego, OR Tap Water Quality 2026

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

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

Main Utility: Lake Oswego Municipal Water PWSID: OR4100457 Updated: 2026 Q2
✅

No federal limits exceeded on record

Lead was not detected and no violations are open. No PFAS was detected.

A

Lake Oswego earns an A for water quality

Graded on violations, lead, and PFAS, with state inspection findings.

Lead: not detected
PFAS tested, none detected
3 violations since 2015, 0 health-based
No violations currently open
Lake Oswego's lead level vs. all Oregon community water systems
0 ppb5 ppb10 ppb15 ppb
Lead level: Not detected — 0% of the federal action level
✓ Lower lead than % of Oregon utilities
Population Served
37087
~13000 connections
Water Source
Surface water
Purchased from another system — SDWIS source code SWP
Active Violations
0
3 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
Consumer Confidence Rule OTHER — — 2025 Resolved
Consumer Confidence Rule OTHER — — 2024 Resolved
Bromate MONITORING AND REPORTING — 0.010 mg/L 2019 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

3 violations are on record since 2015, of which 0 were health-based. All have been resolved and none remain open.

About the Main Water System

Utility Lake Oswego Municipal Water
PWSID OR4100457
Water source Surface water — Purchased from another system — SDWIS source code SWP
Population served 37,087
Service connections 13,000
Systems serving this area 9
Regulator State primacy agency
Data through 2026 Q2 — EPA SDWIS

Frequently Asked Questions

Is Lake Oswego tap water safe to drink? ▼
No federal limit is exceeded on record. No violations are currently open.
Does Lake Oswego water have PFAS? ▼
It was tested for the six regulated PFAS compounds and none were detected.
Who supplies water to Lake Oswego? ▼
Lake Oswego Municipal Water (PWSID OR4100457), one of 9 systems serving this area. Surface water. Purchased from another system — SDWIS source code SWP
When was this system last inspected? ▼
It was last inspected on 2025-10-16. No significant deficiencies were recorded.

What Should Lake Oswego 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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