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Warren County, NJ Water Quality

Water quality data for 11 public water systems serving Warren County, New Jersey — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 11 water systems · 20 cities
✅
Excellent — All Systems Performing Well

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

A

Warren County Earns a A

Warren County: 20 communities across 11 water systems. 100.0% have no open violations.

  • Median lead where detected: 1.00 ppb
  • 11 communities with a lead detection, 9 reporting none detected
  • 4 communities with PFAS above the federal limit
  • 0 with significant inspection deficiencies
  • 100.0% of communities have no open violations
1 ppb
Median Lead Level
County-wide, 90th percentile
11
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
  • Phillipsburg
    Not detected
    No federal limits exceeded on record
    A
  • Hackettstown
    1.00 ppb
    No federal limits exceeded on record
    A
  • Lopatcong
    Not detected
    No federal limits exceeded on record
    A
  • Mansfield
    1.00 ppb
    No federal limits exceeded on record
    A
  • Greenwich
    Not detected
    No federal limits exceeded on record
    A
⚠ Needs Attention
  • Oxford
    2.21 ppb
    Copper above the 1,300 ppb action level
    C
  • Washington
    1.00 ppb
    PFAS above the limit at 3 of 6 sampling points
    B
  • Washington
    1.00 ppb
    PFAS above the limit at 3 of 6 sampling points
    B
  • Franklin
    1.00 ppb
    PFAS above the limit at 3 of 6 sampling points
    B
  • Port Colden
    1.00 ppb
    PFAS above the limit at 3 of 6 sampling points
    B
County Lead Level — Median 1 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 1 ppb — 6.7% of the federal action level
Systems by Lead Level
Under 5 ppb
9
5 – 10 ppb
1
10 – 15 ppb
1
No Data
9

All Cities in Warren County

Phillipsburg Not detected A
Hackettstown 1.00 ppb A
Lopatcong Not detected A
Washington 1.00 ppb B
Washington 1.00 ppb B
Mansfield 1.00 ppb A
Greenwich Not detected A
Allamuchy 4.00 ppb A
Independence 1.00 ppb A
Belvidere Not detected B
Alpha 12.00 ppb B
Pohatcong Not detected A
Franklin 1.00 ppb B
White Not detected B
Blairstown 5.93 ppb B
Oxford 2.21 ppb C
Port Colden 1.00 ppb B
Harmony Not detected B
Frelinghuysen Not detected B
Knowlton Not detected A
Showing 20 cities
No active violations Active violations

About Warren County Drinking Water

Warren County is served by 11 water systems covering 20 communities. No community here has an open violation on record.

Of the communities reporting lead results, 11 recorded a detection, with a median of 1.00 ppb — 7% of the federal action level. 9 reported none detected, which means below the laboratory limit rather than an absence of lead.

4 of 20 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 Warren County tap water safe to drink?▼
No community in Warren County has an open violation on record. 4 of 20 have PFAS above the federal limit, which is the main open concern.
What is the lead level in Warren County?▼
Among communities with a detection the median is 1.00 ppb, 7% of the 15 ppb action level. 9 reported none detected and 0 reported no result.
How many water systems serve Warren County?▼
11 community water systems serve 20 communities here.
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