States › Wisconsin › Ozaukee County

Ozaukee County, WI Water Quality

Water quality data for 9 public water systems serving Ozaukee County, Wisconsin — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 9 water systems · 14 cities
✅
Excellent — All Systems Performing Well

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

A

Ozaukee County Earns a A

Ozaukee County: 14 communities across 9 water systems. 100.0% have no open violations.

  • Median lead where detected: 3.30 ppb
  • 12 communities with a lead detection, 2 reporting none detected
  • 1 communities with PFAS above the federal limit
  • 0 with significant inspection deficiencies
  • 100.0% of communities have no open violations
3.3 ppb
Median Lead Level
County-wide, 90th percentile
9
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
  • Grafton
    3.30 ppb
    No federal limits exceeded on record
    A
  • Mequon
    0.52 ppb
    No federal limits exceeded on record
    A
  • Fredonia
    Not detected
    No federal limits exceeded on record
    B
  • Thiensville
    0.72 ppb
    No federal limits exceeded on record
    B
  • Fredonia
    Not detected
    No federal limits exceeded on record
    B
⚠ Needs Attention
  • Saukville
    7.60 ppb
    PFAS above the limit at 2 of 5 sampling points
    C
  • Cedarburg
    7.60 ppb
    Copper above the 1,300 ppb action level
    B
  • Cedarburg
    7.60 ppb
    Copper above the 1,300 ppb action level
    B
  • Port Washington
    5.90 ppb
    Lead at 5.90 ppb, above a third of the action level
    A
  • Port Washington
    5.90 ppb
    Lead at 5.90 ppb, above a third of the action level
    A
County Lead Level — Median 3.3 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 3.3 ppb — 22% of the federal action level
Systems by Lead Level
Under 5 ppb
7
5 – 10 ppb
5
No Data
2

All Cities in Ozaukee County

Port Washington 5.90 ppb A
Cedarburg 7.60 ppb B
Grafton 3.30 ppb A
Saukville 7.60 ppb C
Mequon 0.52 ppb A
Belgium 1.30 ppb B
Fredonia Not detected B
Thiensville 0.72 ppb B
Cedarburg 7.60 ppb B
Fredonia Not detected B
Grafton 3.30 ppb A
Port Washington 5.90 ppb A
Saukville 1.55 ppb B
Belgium 1.30 ppb B
Showing 14 cities
No active violations Active violations

About Ozaukee County Drinking Water

Ozaukee County is served by 9 water systems covering 14 communities. No community here has an open violation on record.

Of the communities reporting lead results, 12 recorded a detection, with a median of 3.30 ppb — 22% of the federal action level. 2 reported none detected, which means below the laboratory limit rather than an absence of lead.

1 of 14 communities have PFAS above the limits EPA set in 2024, measured as a running annual average at each sampling point. State inspectors recorded no significant deficiencies.

Frequently Asked Questions

Is Ozaukee County tap water safe to drink?▼
No community in Ozaukee County has an open violation on record. 1 of 14 have PFAS above the federal limit, which is the main open concern.
What is the lead level in Ozaukee County?▼
Among communities with a detection the median is 3.30 ppb, 22% of the 15 ppb action level. 2 reported none detected and 0 reported no result.
How many water systems serve Ozaukee County?▼
9 community water systems serve 14 communities here.
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