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Washington County, OR Water Quality

Water quality data for 14 public water systems serving Washington County, Oregon — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 14 water systems · 27 cities
✅
Excellent — All Systems Performing Well

Water quality across the county is outstanding with minimal violations and very low lead levels.

A

Washington County Earns a A

Washington County: 27 communities across 14 water systems. 100.0% have no open violations.

  • Median lead where detected: 4.50 ppb
  • 23 communities with a lead detection, 4 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 10 with significant inspection deficiencies
  • 100.0% of communities have no open violations
4.5 ppb
Median Lead Level
County-wide, 90th percentile
14
Water Systems
Active CWS & NTNCWS
100%
Violation-Free
No active violations on record
How we grade counties: MyWaterIQ uses EPA SDWIS enforcement data — actual MCL violations and lead test results — not the aspirational MCLG targets used by some sites. A grade reflects real compliance history, not theoretical risk. Learn more →

Cities by Water Quality

⭐ Best Performing
  • Hillsboro
    Not detected
    No federal limits exceeded on record
    A
  • Beaverton
    2.60 ppb
    No federal limits exceeded on record
    A
  • Tigard
    0.85 ppb
    No federal limits exceeded on record
    A
  • Tualatin
    4.93 ppb
    No federal limits exceeded on record
    A
  • Forest Grove
    2.90 ppb
    No federal limits exceeded on record
    A
⚠ Needs Attention
  • Aloha
    4.50 ppb
    Copper above the 1,300 ppb action level
    B
  • Bethany
    4.50 ppb
    Copper above the 1,300 ppb action level
    B
  • Cedar Mill
    4.50 ppb
    Copper above the 1,300 ppb action level
    B
  • Oak Hills
    4.50 ppb
    Copper above the 1,300 ppb action level
    B
  • Rockcreek
    4.50 ppb
    Copper above the 1,300 ppb action level
    B
County Lead Level — Median 4.5 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 4.5 ppb — 30% of the federal action level
Systems by Lead Level
Under 5 ppb
21
5 – 10 ppb
2
No Data
4

All Cities in Washington County

Hillsboro Not detected A
Beaverton 2.60 ppb A
Aloha 4.50 ppb B
Tigard 0.85 ppb A
Bethany 4.50 ppb B
Tualatin 4.93 ppb A
Forest Grove 2.90 ppb A
Sherwood 1.30 ppb A
Cedar Mill 4.50 ppb B
Cornelius Not detected A
Oak Hills 4.50 ppb B
Bull Mountain 0.85 ppb A
Rockcreek 4.50 ppb B
West Haven-Sylvan 4.50 ppb B
Cedar Hills 4.50 ppb B
Garden Home-Whitford 4.50 ppb B
West Slope 4.89 ppb A
Marlene Village 4.50 ppb B
King City 0.85 ppb A
Metzger 4.50 ppb B
Raleigh Hills 4.89 ppb A
North Plains Not detected B
Banks 3.00 ppb B
Durham 0.85 ppb A
Gaston Not detected B
Cherry Grove 6.40 ppb B
Dilley 6.40 ppb B
Showing 27 cities
No active violations Active violations

About Washington County Drinking Water

Washington County is served by 14 water systems covering 27 communities. No community here has an open violation on record.

Of the communities reporting lead results, 23 recorded a detection, with a median of 4.50 ppb — 30% of the federal action level. 4 reported none detected, which means below the laboratory limit rather than an absence of lead.

No community here has PFAS above the federal limit on record. State inspectors recorded significant deficiencies at 10 of them.

Frequently Asked Questions

Is Washington County tap water safe to drink?▼
No community in Washington County has an open violation on record. No community has PFAS above the federal limit on record.
What is the lead level in Washington County?▼
Among communities with a detection the median is 4.50 ppb, 30% of the 15 ppb action level. 4 reported none detected and 0 reported no result.
How many water systems serve Washington County?▼
14 community water systems serve 27 communities here.
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