States › Missouri › Jefferson County

Jefferson County, MO Water Quality

Water quality data for 20 public water systems serving Jefferson County, Missouri — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 20 water systems · 25 cities
✅
Excellent — All Systems Performing Well

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

A

Jefferson County Earns a A

Jefferson County: 25 communities across 20 water systems. 100.0% have no open violations.

  • Median lead where detected: 2.53 ppb
  • 18 communities with a lead detection, 7 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 14 with significant inspection deficiencies
  • 100.0% of communities have no open violations
2.53 ppb
Median Lead Level
County-wide, 90th percentile
20
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
  • Barnhart
    Not detected
    No federal limits exceeded on record
    A
  • Imperial
    3.86 ppb
    No federal limits exceeded on record
    A
  • Pevely
    2.21 ppb
    No federal limits exceeded on record
    B
  • Herculaneum
    1.43 ppb
    No federal limits exceeded on record
    A
  • Cedar Hill
    2.48 ppb
    No federal limits exceeded on record
    A
⚠ Needs Attention
  • Crystal City
    Not detected
    1 significant inspection deficiency
    C
  • Arnold
    7.25 ppb
    1 significant inspection deficiency
    B
  • Briarwood Estates
    7.70 ppb
    1 significant inspection deficiency
    B
  • Summer Set
    1.63 ppb
    1 significant inspection deficiency
    B
  • Festus
    Not detected
    1 significant inspection deficiency
    A
County Lead Level — Median 2.53 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 2.53 ppb — 16.9% of the federal action level
Systems by Lead Level
Under 5 ppb
16
5 – 10 ppb
2
No Data
7

All Cities in Jefferson County

Arnold 7.25 ppb B
Festus Not detected A
De Soto 1.46 ppb A
Murphy Not detected A
Barnhart Not detected A
High Ridge Not detected A
Imperial 3.86 ppb A
Crystal City Not detected C
Pevely 2.21 ppb B
Herculaneum 1.43 ppb A
Byrnes Mill 2.93 ppb A
Hillsboro 4.28 ppb B
Cedar Hill 2.48 ppb A
Raintree Plantation 1.52 ppb B
Summer Set 1.63 ppb B
Olympian Village 1.13 ppb A
Horine 3.94 ppb A
LaBarque Creek 2.10 ppb B
Scotsdale 2.93 ppb A
Parkdale Not detected A
Briarwood Estates 7.70 ppb B
Lake Tekakwitha 2.00 ppb B
Kimmswick 3.86 ppb A
Cedar Hill Lakes 2.58 ppb B
Peaceful Village Not detected A
Showing 25 cities
No active violations Active violations

About Jefferson County Drinking Water

Jefferson County is served by 20 water systems covering 25 communities. No community here has an open violation on record.

Of the communities reporting lead results, 18 recorded a detection, with a median of 2.53 ppb — 17% of the federal action level. 7 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 14 of them.

Frequently Asked Questions

Is Jefferson County tap water safe to drink?▼
No community in Jefferson County has an open violation on record. No community has PFAS above the federal limit on record.
What is the lead level in Jefferson County?▼
Among communities with a detection the median is 2.53 ppb, 17% of the 15 ppb action level. 7 reported none detected and 0 reported no result.
How many water systems serve Jefferson County?▼
20 community water systems serve 25 communities here.
← Back to Missouri water quality overview