Sonora, CA 95370

14 water systems • 37,743 residents

Excellent water quality with minimal contaminants

A

Score: 87/100

Graded on EPA violations, contaminants, severity, compliance, and enforcement history. See methodology.

Data updated June 2026 • Sources: EPA ECHO and EPA Envirofacts

20

Contaminants Detected

197

Violations on Record

53

Health-Based Violations

0

Recent Violations

Grade Breakdown

Contaminant Count5 / 25
Violation History23 / 25
Contaminant Severity20 / 25
System Compliance0 / 15
Enforcement History0 / 10
Total Score87%

87 / 100 points

Recommended Water Filters

  • ✓Point-of-Use Carbon Filter (NSF-certified for lead)
  • ✓Reverse Osmosis or Ion Exchange Filter
  • ✓Ultraviolet (UV) Purification
  • ✓Activated Carbon Filter (disinfection byproducts)
Compare filter types in our Filter Guide →

Consult a water quality specialist for personalized recommendations.

Sonora vs CA & National Average

Detected Contaminants

20 contaminants detected across water systems serving this ZIP code

ContaminantCategory
NitrateAgricultural
Total Haloacetic Acids (HAA5)Disinfection Byproduct
TTHMDisinfection Byproduct
Antimony, TotalHeavy Metal
ArsenicHeavy Metal
BariumHeavy Metal
Beryllium, TotalHeavy Metal
CadmiumHeavy Metal
ChromiumHeavy Metal
Lead and Copper RuleHeavy Metal
LEAD AND COPPER RULE REVISIONSHeavy Metal
MercuryHeavy Metal
NickelHeavy Metal
SeleniumHeavy Metal
Thallium, TotalHeavy Metal
Coliform (TCR)Microorganism
Revised Total Coliform RuleMicroorganism
Interim Enhanced Surface Water Treatment RuleOther
Surface Water Treatment RuleOther
Gross Alpha, Excl. Radon and URadiological

Water System Information

Systems Serving This ZIP:
BELLEVIEW OAKS MUTUAL WATER CO, TUD - COLUMBIA WATER SYSTEM, TUD-WARDS FERRY RANCHES, TUD-PEACEFUL PINES WATER SYSTEM, TUD - SONORA/JAMESTOWN WATER SYSTEM +5 more
Population Served:
37,743
Systems With Violations:
14 of 14
Major Violations:
38
Enforcement Actions:
165

Nearby Areas

95379

Tuolumne • 4.9 mi away

A

95373

Standard • 5.9 mi away

A

95327

Jamestown • 6.8 mi away

B

95310

Columbia • 7 mi away

A

95372

Soulsbyville • 7.1 mi away

A

95383

Twain Harte • 12.6 mi away

A

Frequently Asked Questions

What does the grade mean?

Our A–F grade ranks this ZIP code's water quality against every other analyzed ZIP in the country, based on EPA data. A = among the best, F = among the most troubled.

Is my tap water safe to drink?

Water systems regulated by the EPA must comply with Safe Drinking Water Act standards. However, if you're concerned about water quality, consider a water filter appropriate for your contaminants.

How often is the data updated?

We update our data quarterly with the latest EPA ECHO and Envirofacts data. Historical violations are tracked to identify patterns.

What filters do you recommend?

Filter recommendations are based on detected contaminants in your area. See our Filter Guide for detailed information about different filter types.