Contra Costa Water District
EPA ID: CA0710003 · 198,000 people served · 23 ZIP codes
ZipCheckup's reading of EPA records for Contra Costa Water District (CA0710003): no drinking-water violations recorded since 2021. Across the reporting cycles included in federal data, Contra Costa Water District has no EPA violation entries - the file covers a service population of approximately 198,000 residents and says nothing about individual household plumbing.
Data: EPA SDWIS
Service Area Map
Coverage area for Contra Costa Water District Source: EPA SDWIS service area boundaries.
Service area boundary
Demographics of ZIP Codes Served
The ZIP codes associated with Contra Costa Water District have a median household income of $128,948 and about 744,050 residents live in those ZIP codes (Census; not the number of people this system supplies). Approximately 62% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
🌊 Where Does Your Water Come From?
Contra Costa Water District's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
Superfund Proximity Note: This service area ranks in the 60th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
PFAS in ZIP Codes This System Serves
PFAS ("forever chemicals") have been reported in samples from water systems associated with the ZIP codes in this system's area. These results can come from other water systems serving the same ZIP codes; check the UCMR5 section for any results reported for this system. 11 detections recorded. 1 detection is above the level of a federal PFAS MCL (4 ppt for PFOA and PFOS), with compliance required from 2029.
Comparable Water Systems
Similar-sized systems in California
Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
Contra Costa Water District (EPA ID: CA0710003) is a community water system in California that serves approximately 198,000 people from surface water sources.
This system provides water to 23 ZIP codes across 17 communities.
Violation History
Lead & Copper
EPA Lead and Copper Rule evidence attributed directly to this water system:
| Lead Level | Exceeds Action Level | Sample Date |
|---|---|---|
| 0.0031 mg/L | No | 2025-12-31 |
No copper action-level exceedance record appears for this PWSID in the accepted LCR snapshot. This does not establish a clean copper measurement.
Radon Risk in Service Area
22 of 23 ZIP records with known zones are in EPA Radon Zone 2. 1 of 23 ZIP records with known zones is in EPA Radon Zone 3.
The EPA recommends testing all homes regardless of radon zone. County radon zones cannot replace an in-home radon test.
ZIP Codes Served
Coverage: Service area ZIP codes sourced from EPA Community Water System Service Area Boundaries v3 (March 2026 release). These ZIPs reflect the actual deployment footprint recorded by CA or modeled from parcel and building-footprint data.
- 94506 - Danville
- 94509 - Antioch
- 94511 - Bethel Island
- 94513 - Brentwood
- 94517 - Clayton
- 94518 - Concord
- 94519 - Concord
- 94520 - Concord
- 94521 - Concord
- 94523 - Pleasant Hill
- 94525 - Crockett
- 94531 - Antioch
- 94547 - Hercules
- 94548 - Knightsen
- 94549 - Lafayette
- 94553 - Martinez
- 94561 - Oakley
- 94565 - Pittsburg
- 94569 - Port Costa
- 94596 - Walnut Creek
- 94597 - Walnut Creek
- 94598 - Walnut Creek
- 95219 - Stockton
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View available EPA compliance records for Contra Costa Water District (CA0710003) on EPA.gov.
Frequently Asked Questions
Is Contra Costa Water District water safe to drink?
The accepted 2026Q2 ECHO snapshot contains zero violation records for Contra Costa Water District in the inclusive 2021-2026 record-year window. This is a compliance-record finding, not a guarantee about water at a specific tap.
How many people does Contra Costa Water District serve?
Contra Costa Water District serves approximately 198,000 people across 23 ZIP codes in California.
Where does Contra Costa Water District get its water?
The primary water source is surface water.
Federal UCMR5 PFAS Monitoring: No PFAS Reported Above Reporting Levels
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). No PFAS compounds were reported above UCMR5 minimum reporting levels.
EPA's April 2024 PFAS rule sets MCLs of 4 ppt for PFOA and PFOS and 10 ppt for PFHxS, PFNA and HFPO-DA (GenX); water systems must comply from 2029. Other PFAS compounds have no individual federal MCL. A state standard is shown only where this system's state has its own enforceable PFAS limit. Detection results are EPA UCMR5 samples, not a measurement at your tap.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
Frequently Asked Questions
How to cite this page
ZipCheckup. (n.d.). Contra Costa Water District, CA: Serves 198K People. https://zipcheckup.com/water-system/ca0710003/
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