Mariposa, CA 95338

5 water systems • 3,695 residents

Moderate water quality - consider filtration

C

Score: 50/100

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

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

11

Contaminants Detected

288

Violations on Record

221

Health-Based Violations

0

Recent Violations

Grade Breakdown

Contaminant Count14 / 25
Violation History18 / 25
Contaminant Severity0 / 25
System Compliance0 / 15
Enforcement History0 / 10
Total Score50%

50 / 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.

Mariposa vs CA & National Average

Detected Contaminants

11 contaminants detected across water systems serving this ZIP code

ContaminantCategory
NitrateAgricultural
Total Haloacetic Acids (HAA5)Disinfection Byproduct
TTHMDisinfection Byproduct
Lead and Copper RuleHeavy Metal
LEAD AND COPPER RULE REVISIONSHeavy Metal
Coliform (TCR)Microorganism
Revised Total Coliform RuleMicroorganism
CARBON, TOTALOther
Consumer Confidence RuleOther
Surface Water Treatment RuleOther
Radium-228Radiological

Water System Information

Systems Serving This ZIP:
YOSEMITE WEST WATER SYSTEM, MARIPOSA PUBLIC UTILITY DIST, MPWD-COULTERVILLE CSA 1, MARIPOSA PINES MUTUAL, PONDEROSA BASIN MUTUAL WTR CO
Population Served:
3,695
Systems With Violations:
5 of 5
Major Violations:
24
Enforcement Actions:
284

Nearby Areas

95311

Coulterville • 11.5 mi away

A

95389

Yosemite National Park • 18.3 mi away

A

95321

Groveland • 20.7 mi away

A

93644

Oakhurst • 24.3 mi away

C

95333

Le Grand • 24.3 mi away

B

93653

Raymond • 24.5 mi away

D

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.