States › California › Contra Costa County

Contra Costa County, CA Water Quality

Water quality data for 10 public water systems serving Contra Costa County, California — based on EPA SDWIS enforcement records, lead testing results, and health-based violation history.

📅 2026 Report 🔄 Data updated 2026 Q2 📍 10 water systems · 53 cities
✅
Excellent — All Systems Performing Well

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

A

Contra Costa County Earns a A

Contra Costa County: 53 communities across 10 water systems. 100.0% have no open violations.

  • Median lead where detected: 3.10 ppb
  • 16 communities with a lead detection, 37 reporting none detected
  • 0 communities with PFAS above the federal limit
  • 0 with significant inspection deficiencies
  • 100.0% of communities have no open violations
3.1 ppb
Median Lead Level
County-wide, 90th percentile
10
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
  • Norris Canyon
    Not detected
    No federal limits exceeded on record
    A
  • Concord
    3.10 ppb
    No federal limits exceeded on record
    A
  • Richmond
    Not detected
    No federal limits exceeded on record
    A
  • Brentwood
    Not detected
    No federal limits exceeded on record
    A
  • Antioch
    3.10 ppb
    No federal limits exceeded on record
    A
⚠ Needs Attention
  • Norris Canyon
    Not detected
    No federal limits exceeded on record
    A
  • Concord
    3.10 ppb
    No federal limits exceeded on record
    A
  • Richmond
    Not detected
    No federal limits exceeded on record
    A
  • Brentwood
    Not detected
    No federal limits exceeded on record
    A
  • Antioch
    3.10 ppb
    No federal limits exceeded on record
    A
County Lead Level — Median 3.1 ppb
Based on most recent 90th percentile lead tests across all reporting systems
0 ppb5 ppb10 ppb15 ppb
County median: 3.1 ppb — 20.7% of the federal action level
Systems by Lead Level
Under 5 ppb
16
No Data
37

All Cities in Contra Costa County

Concord 3.10 ppb A
Richmond Not detected A
Brentwood Not detected A
Antioch 3.10 ppb A
San Ramon Not detected A
Walnut Creek Not detected A
Danville Not detected A
Pittsburg Not detected A
San Pablo Not detected A
Pleasant Hill 3.10 ppb A
Hercules Not detected A
El Cerrito Not detected A
Lafayette Not detected A
Martinez 3.10 ppb A
Oakley 1.90 ppb B
Orinda Not detected A
Pinole Not detected A
Moraga Not detected A
El Sobrante Not detected A
Discovery Bay Not detected A
Alamo Not detected A
Bay Point 3.10 ppb A
Clayton 3.10 ppb A
Blackhawk Not detected A
Rodeo Not detected A
Contra Costa Centre 3.10 ppb A
Saranap Not detected A
Kensington Not detected A
Tara Hills Not detected A
Camino Tassajara Not detected A
Vine Hill 3.10 ppb A
Pacheco 3.10 ppb A
North Richmond Not detected A
San Miguel Not detected A
East Richmond Heights Not detected A
Reliez Valley Not detected A
Crockett Not detected A
Montalvin Manor Not detected A
Rollingwood Not detected A
Bayview Not detected A
Mountain View 3.10 ppb A
Acalanes Ridge Not detected A
Castle Hill Not detected A
Diablo Not detected A
Shell Ridge Not detected A
Clyde 3.10 ppb A
North Gate 3.10 ppb A
Knightsen 1.10 ppb B
Bethel Island 0.50 ppb B
Alhambra Valley Not detected A
Byron Not detected B
Port Costa 3.10 ppb A
Norris Canyon Not detected A
Showing 53 cities
No active violations Active violations

About Contra Costa County Drinking Water

Contra Costa County is served by 10 water systems covering 53 communities. No community here has an open violation on record.

Of the communities reporting lead results, 16 recorded a detection, with a median of 3.10 ppb — 21% of the federal action level. 37 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 no significant deficiencies.

Frequently Asked Questions

Is Contra Costa County tap water safe to drink?▼
No community in Contra Costa County has an open violation on record. No community has PFAS above the federal limit on record.
What is the lead level in Contra Costa County?▼
Among communities with a detection the median is 3.10 ppb, 21% of the 15 ppb action level. 37 reported none detected and 0 reported no result.
How many water systems serve Contra Costa County?▼
10 community water systems serve 53 communities here.
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