States › California › San Joaquin County

San Joaquin County, CA Water Quality

Water quality data for 21 public water systems serving San Joaquin County, California — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 21 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

San Joaquin County Earns a A

San Joaquin County: 25 communities across 21 water systems. 100.0% have no open violations.

  • Median lead where detected: 3.70 ppb
  • 2 communities with a lead detection, 23 reporting none detected
  • 4 communities with PFAS above the federal limit
  • 0 with significant inspection deficiencies
  • 100.0% of communities have no open violations
3.7 ppb
Median Lead Level
County-wide, 90th percentile
21
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
  • Tracy
    Not detected
    No federal limits exceeded on record
    A
  • Mountain House
    Not detected
    No federal limits exceeded on record
    A
  • Garden Acres
    Not detected
    No federal limits exceeded on record
    A
  • Country Club
    Not detected
    No federal limits exceeded on record
    A
  • August
    Not detected
    No federal limits exceeded on record
    A
⚠ Needs Attention
  • Lathrop
    Not detected
    PFAS above the limit at 1 of 2 sampling points
    C
  • Ripon
    Not detected
    PFAS above the limit at 1 of 5 sampling points
    C
  • Lodi
    Not detected
    PFAS above the limit at 1 of 23 sampling points
    B
  • Manteca
    0.40 ppb
    PFAS above the limit at 2 of 10 sampling points
    B
  • Stockton
    Not detected
    3 health-based violations since 2015
    B
County Lead Level — Median 3.7 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 3.7 ppb — 24.7% of the federal action level
Systems by Lead Level
Under 5 ppb
1
5 – 10 ppb
1
No Data
23

All Cities in San Joaquin County

Stockton Not detected B
Tracy Not detected A
Lodi Not detected B
Manteca 0.40 ppb B
Mountain House Not detected A
Lathrop Not detected C
Garden Acres Not detected A
Country Club Not detected A
August Not detected A
Ripon Not detected C
Lincoln Village Not detected A
Escalon Not detected A
Kennedy Not detected A
Lockeford Not detected B
Linden Not detected B
Taft Mosswood Not detected A
Thornton Not detected B
Morada Not detected B
Terminous Not detected B
Acampo Not detected B
Victor Not detected B
Farmington Not detected B
French Camp Not detected B
Woodbridge Not detected B
Collierville 7.00 ppb B
Showing 25 cities
No active violations Active violations

About San Joaquin County Drinking Water

San Joaquin County is served by 21 water systems covering 25 communities. No community here has an open violation on record.

Of the communities reporting lead results, 2 recorded a detection, with a median of 3.70 ppb — 25% of the federal action level. 23 reported none detected, which means below the laboratory limit rather than an absence of lead.

4 of 25 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 San Joaquin County tap water safe to drink?▼
No community in San Joaquin County has an open violation on record. 4 of 25 have PFAS above the federal limit, which is the main open concern.
What is the lead level in San Joaquin County?▼
Among communities with a detection the median is 3.70 ppb, 25% of the 15 ppb action level. 23 reported none detected and 0 reported no result.
How many water systems serve San Joaquin County?▼
21 community water systems serve 25 communities here.
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