Contra Costa County property record for 509 William Way, Martinez, CA 94553
| Property Type | Single Family Home |
|---|---|
| Details | 5 bd · 3.5 ba · 3,003 sqft · built 2023 |
| Lot Size | 0.174 acres (7,593 sqft) |
| Owner | 2 Individual Names on File |
| Last Sale | $1,472,500 (Nov 2023) |
| Tax Bill | $21,475 (2025) |
| Deeds & Mortgages | Nov 2023 Sale & Mortgage |
| Flood Zone | Zone X (minimal risk) |
| APN | 162-580-033-7 |
| Primary APN | 162-580-033-7 |
|---|---|
| Alternative APN |
|
| Bedrooms | 5 Beds |
|---|---|
| Full Baths | 3.5 Baths |
| Half Baths | 1 Half Bath |
| Total Rooms | 10 Rooms |
| Stories | 2 Stories |
| Building Area | 3,003 sqft Living Area |
| 1st Floor Area | 1,968 sqft |
| 2nd Floor Area | 1,035 sqft |
| Year Built | Built 2023 |
|---|---|
| Effective Year Built | Effective 2023 |
| Lot Area | 7,593 sqft (0.174 acres) |
| Garage Type | Attached |
| Garage Area | 439 sqft |
| Parking Spaces | 2 Parking Spaces |
| Street Address | 509 WILLIAM WAY |
|---|---|
| City | MARTINEZ |
| State | CA |
| Zip | 94553-4764 |
| Property Category | Residential |
| Property Type | Residential > Single Family > Home |
| Legal Description | T9358 L33 |
| Legal Subdivision | TRADITIONS/THE MDW SUB 9358 |
| Legal Tract | 9358 |
| Jurisdiction | CONTRA COSTA CA |
| Township / Civil Division | CENTRAL CONTRA COSTA |
| Census Block Group | 3 |
| Census Block | 3014 |
| Census Tract | 321101 |
509 William Way is owned and occupied by two individuals who bought it in November 2023.
Source: Contra Costa County records, as of July 14, 2026
| Owner of Record | 2 Individual Names on File |
|---|---|
| Mailing Address | 509 WILLIAM WAY, MARTINEZ, CA 94553-4764 |
| Occupancy | Owner Occupied |
| Owner Type | Individual |
| Vesting | Joint Tenants |
Owner names and exact recorded amounts are on file and can be viewed instantly on this page with a free 10-day trial.
| Deed Names | 2 Names on Deed |
|---|---|
| Last Sale | Nov 22, 2023 · Amount on File |
| Deed Sale | Nov 22, 2023 · Amount on File |
| Deed Document Number | 2023124956 |
| Record Updated | Sep 20, 2026 |
| Document Type | Grant Deed |
|---|---|
| Jurisdiction | CONTRA COSTA CA |
| Recording Date | Nov 22, 2023 |
| Property Address | 509 WILLIAM WAY, MARTINEZ, CA 94553-4764 |
| Document Number | 0000124956 |
| Map Reference | MB 548 PG 21 |
| Instrument Date | Oct 24, 2023 |
| Instrument | 2023-124956 |
| Transaction Type | Transfer |
| Record Updated | Dec 13, 2023 |
| Title Company | OLD REPUBLIC TITLE, OLD REPUBLIC TITLE COMPANY |
| Amount | Amount on Record |
|---|---|
| Downpayment | Downpayment on Record |
| Loan-to-Value (LTV) | LTV on Record |
| Tax | $0.00 |
| Amount Accuracy | Rounded by County |
| Additional |
|
| Name | Verified Name |
|---|
| Name | Verified Name |
|---|---|
| Relationship | Joint Tenants |
| Address | 509 WILLIAM WAY, MARTINEZ, CA 94553-4764 |
| Document Number | 0000124957 |
|---|---|
| Date | Nov 22, 2023 |
| Instrument | 2023-124957 |
| Name | US BANK NA |
|---|---|
| Type | Bank |
| Type | Conventional Mortgage |
|---|---|
| Amount | Amount on Record |
| Term | 361 Months |
| Due | Dec 1, 2053 |
The 2025 property tax bill for 509 William Way was $21,475.
Source: Contra Costa County assessment roll, as of July 14, 2026
| Type | Name |
|---|---|
| State | California |
| County | Contra Costa County |
| Municipality | Martinez City |
| Unified School District | Mount Diablo Unified School District (KG - 12) |
| Year | Tax Bill | Assessed Value |
|---|---|---|
| 2026 | $1,531,468 (+2%) Land $1,011,268 Building $520,200 | |
| 2025 | $21,475.00 | $1,501,440 Land $991,440 Building $510,000 |
| 2023 | $5,448.00 (+193.85%) | $215,377 Land $215,377 |
| 2022 | $1,854.00 |
Assessed value and assessed market value are set for property tax purposes, not market price estimates; both are a fraction of this property's market value.
FEMA maps place 509 William Way in Zone X, an area of minimal flood risk.
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 | 1 in force |
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.
The area around 509 William Way has no burnable land within ember reach, so its wildfire risk is not rated.
Source: USDA Forest Service Wildfire Risk to Communities (2nd edition), as of 2024
| Wildfire Risk | Not rated no burnable land within ember reach |
|---|
Values cover an area roughly 900 ft across, not the parcel itself; insurers use their own ratings.
Source: EPA Safe Drinking Water Information System, as of September 2026
| Water System | CITY OF MARTINEZ serves 31,015 people · EPA ID CA0710006 |
|---|---|
| Water Source | Purchased surface water from CONTRA COSTA WATER DISTRICT |
| Last State Inspection | Oct 2025 |
| Lead | Under 1 ppb (2023–2025) 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 528 locations within half a mile, as of December 31, 2025
| Provider | Max Down / Up (Mbps) |
|---|---|
| Xfinity Cable | 2,000 / 250 |
| Astound Broadband Fiber · Cable in parts of the area | 1,500 / 1,500 |
| Unwired Fixed Wireless | 300 / 25 |
| T-Mobile Fixed Wireless | 100 / 20 |
| AT&T DSL · Fiber in parts of the area | 100 / 20 |
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