PlainWater
Counties → California

Contra Costa County, California

Water Systems
86
Population Served
565,242
Total Violations
1,010
312 health-based
PFAS Detected
4
of 8 tested

Violation Analysis

79.1%
Systems with Violations
11.7
Avg Violations per System
30.9%
Health-Based Violations

Water Source Types

GW
39 systems (45%)
SW
11 systems (13%)

PFAS Contamination

8
Systems Tested
4
PFAS Detected
50.0%
Detection Rate

PFAS (per- and polyfluoroalkyl substances) are persistent chemicals found in drinking water. The EPA has set enforceable limits for several PFAS compounds under UCMR5 monitoring.

Compliance Snapshot

Contra Costa California water systems by violation status, EPA SDWIS records.

No violations on record (6) One or more violations (44)

Violation history is cumulative, many flagged systems have already returned to compliance. Detail pages show per-system context.

Water Systems

System Name Population Violations PFAS
Contra Costa Water District 198,000 4 Clean
City of Antioch 115,074 6 Clean
Brentwood 64,513 41 Clean
City of Pittsburg 62,500 5 Clean
Diablo Water District 43,357 0 Clean
City of Martinez 30,997 3 Clean
Golden State Water Company - Bay Point 23,731 7 Clean
Town of Discovery Bay 16,790 6 Clean
Pleasantimes Mutual Water Co 644 9 -
Excelsior Middle School 600 8 -
Clayton Palms Water 549 7 -
Willow Mobile Home Park 481 8 -
Willow Park Marina 380 16 -
Mount Diablo State Park 364 24 -
Knightsen Elementary School 350 38 -
Orwood Resort 350 11 -
Delta Mutual Water Company 333 24 -
Canyon School 238 20 -
Riverview Water Association 230 15 -
Camino Mobilehome 210 16 -
Byron Corners Inc 205 21 -
Country Junction Deli 200 13 -
Bethel Island Estates 200 14 -
Bruns Memorial Amphitheater 200 0 -
Bethel Island Mhc 185 9 -
Los Vaqueros Marina Bldg 180 0 -
Dwr Delta Field Division - Banks Pp 180 4 -
Oakley Mutual Water Company 170 19 -
Big Oak Mobile Home Park Water 156 13 -
Delta Sportsman 150 16 -
Sugar Barge Marina 150 4 -
Farrar Park Property Owners 140 5 -
Riverview Mobile Home Park 126 11 -
Bethel Island Mutual Water Co 123 11 -
Gas N Save 120 44 -
Concord Mt Diablo Trailride Assoc. 120 29 -
Ebrpd Alhambra 115 0 -
Russos Mobile Park 110 13 -
Ebrpd Bay Point Regional Shoreline 105 0 -
Bethel Market 100 16 -
Delta Bar and Grill 100 11 -
Sandmound Mutual 100 12 -
Anglers Subdivision 4 99 11 -
Bella Vista Water Sys 93 18 -
Macs Old House 90 12 -
Ebrpd Round Valley Water System 82 0 -
New Life Marina 80 10 -
Cruiser Haven Marina 75 19 -
Bethel Baptist Church 75 11 -
Bridgehead Cafe 75 21 -

Other Counties in California

Los Angeles County
276 systems · 10,109,089 served · 3,972 violations
San Diego County
197 systems · 3,744,323 served · 4,832 violations
Orange County
46 systems · 3,201,893 served · 507 violations
Riverside County
201 systems · 2,839,125 served · 6,103 violations
San Bernardino County
318 systems · 2,830,626 served · 4,611 violations
Alameda County
27 systems · 2,249,634 served · 275 violations

Drinking Water Guides

Frequently Asked Questions

How many water violations are in Contra Costa County? ▼
Contra Costa County has 1,010 total drinking water violations across 86 water systems, of which 312 are health-based violations. 79.1% of systems have at least one violation.
How many people get water from Contra Costa County systems? ▼
Water systems in Contra Costa County serve approximately 565,242 people through 86 public water systems.
Has PFAS been detected in Contra Costa County water? ▼
Of 8 water systems tested for PFAS in Contra Costa County, 4 had PFAS detected (50.0% detection rate).
What types of water sources supply Contra Costa County? ▼
Water systems in Contra Costa County use GW (39 systems), SW (11 systems) as their primary water sources.
Are health-based violations serious? ▼
Health-based violations indicate that drinking water exceeded Maximum Contaminant Levels (MCLs) set by the EPA or failed treatment technique requirements. 30.9% of Contra Costa County's violations are health-based. Not all violations indicate immediate health risk, but they require corrective action.
Data Sources & Methodology

Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.

Violations are categorized as health-based (Maximum Contaminant Level exceedances, treatment technique failures) or monitoring/reporting violations. Not all violations indicate an immediate health risk.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.