Contra Costa County property record for 511 W 3rd St, Antioch, CA 94509
| Property Type | Commercial Office |
|---|---|
| Details | 1,687 sqft · built 1906 |
| Lot Size | 0.115 acres (5,000 sqft) |
| Owner | 2 Company Names on File |
| Tax Bill | $4,469 (2025) |
| Flood Zone | Zone X (minimal risk) |
| APN | 066-056-017-8 |
| Primary APN | 066-056-017-8 |
|---|---|
| Alternative APN |
|
| Stories | 1 Story |
|---|---|
| Building Area | 1,687 sqft Gross Area |
| 1st Floor Area | 1,687 sqft |
| Year Built | Built 1906 |
|---|---|
| Effective Year Built | Effective 1980 |
| Exterior Material | Stucco |
| Construction Type | Frame |
| Roof Type | Hip |
| Roof Material | Composition Shingle |
| Lot Area | 5,000 sqft (0.115 acres) |
| Garage Area | 910 sqft |
| Street Address | 511 W 3RD ST |
|---|---|
| City | ANTIOCH |
| State | CA |
| Zip | 94509-1275 |
| Property Category | Commercial |
| Property Type | Commercial > Office > Commercial Office |
| Legal Description | TOWN OF ANTIOCH LOT 3 BLK 23 |
| Legal Subdivision | TOWN ANTIOCH |
| Legal Block | 23 |
| Legal Lot Number | 3 |
| Jurisdiction | CONTRA COSTA CA |
| Township / Civil Division | ANTIOCH-PITTSBURG |
| Census Block Group | 3 |
| Census Block | 3027 |
| Census Tract | 305000 |
Source: Contra Costa County assessment roll, as of July 14, 2026
Owner names and exact recorded amounts shown locked on this page are available instantly with a free trial.
| Owner of Record | 2 Company Names on File |
|---|---|
| Mailing Address | 119 W 6TH ST, ANTIOCH, CA 94509-1751 |
| Owner Type | Company |
| Vesting | Trust |
| Deed Names | 2 Verified Names on Deed |
|---|---|
| Last Transfer Date | Jun 24, 2020 |
| Transfer Doc | 0000130398 |
| Record Updated | Sep 20, 2026 |
Source: Contra Costa County assessment roll, as of July 14, 2026
| Type | Name |
|---|---|
| State | California |
| County | Contra Costa County |
| Municipality | Antioch City |
| Unified School District | Antioch Unified School District (KG - 12) |
| Year | Tax Bill | Assessed Value |
|---|---|---|
| 2026 | $272,323 (+3%) Land $90,402 Building $181,921 | |
| 2025 | $4,469.00 (+8.29%) | $264,400 (+4.45%) Land $88,630 Building $175,770 |
| 2023 | $4,127.00 (+1.18%) | $253,141 Land $85,190 Building $167,951 |
| 2022 | $4,079.00 |
Assessed value is set for property tax purposes and is not a market price estimate.
Source: FEMA National Flood Hazard Layer, effective October 12, 2026 · OpenFEMA NFIP redacted claims and policies, as of September 2026
| FEMA Flood Zone | Zone X minimal risk |
|---|---|
| Flood Insurance Requirement | Not required lenders may require it |
| Nearby Flood Policies | 5 in force |
| Nearby Flood Claims | 1 (2017) |
| Most Recent Claim | Feb 2017 · Severe Winter Storms, Flooding, And Mudslides |
Values are read at the parcel center point; flood claims are located to the census block group, not this parcel; lenders make the official flood determination.
Source: USDA Forest Service Wildfire Risk to Communities (2nd edition), as of 2024
| Wildfire Risk | Not rated no burnable land within ember reach |
|---|
Source: EPA Safe Drinking Water Information System, as of September 2026
| Water System | CITY OF ANTIOCH serves 116,781 people · EPA ID CA0710001 |
|---|---|
| Water Source | Surface water |
| Last State Inspection | Jan 2024 |
| Lead | Under 1 ppb (2022–2024) action level 15 ppb |
| Water Quality | None last 10 years |
|---|---|
| Treatment and Procedure | None last 10 years |
| Monitoring and Reporting | None last 3 years |
Results are for the whole water system, not water tested at this address; lead at the tap also depends on the building's own pipes.
Source: FCC Broadband Data Collection, based on 374 locations within half a mile, as of December 31, 2025
| Provider | Max Down / Up (Mbps) |
|---|---|
| AT&T Fiber · DSL in parts of the area | 5,000 / 5,000 |
| Xfinity Cable | 2,000 / 250 |
| Unwired Fixed Wireless | 300 / 25 |
May also be available: T-Mobile USA, Verizon.
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