Suffolk County and Islip Town property record for 21 William Ave, East Islip, NY 11730
| Property Type | Single Family Home |
|---|---|
| Lot Size | 0.25 acres (10,890 sqft) |
| Owner | Individual Name on File |
| Last Sale | $280,000 (Sep 2005) |
| Tax Bill | $8,348 (2024) |
| Flood Zone | Zone X (minimal risk) |
| APN | 472889 372.-4-20 |
| Primary APN | 472889 372.-4-20 |
|---|---|
| Alternative APNs |
|
| Lot Area | 10,890 sqft (0.25 acres) |
|---|---|
| Lot Dimensions | 151 ft deep x 72 ft wide |
| Account Number | 181540 |
|---|---|
| Street Address | 21 WILLIAM AVE |
| City | EAST ISLIP |
| State | NY |
| Zip | 11730-2304 |
| Property Category | Residential |
| Property Type | Residential > Single Family > Home |
| Local Zoning Code | A |
| Legal Description | X2223369Y184367 T061H00000000 |
| Legal Block | 2000 |
| Legal Lot Number | 400 |
| Jurisdiction | SUFFOLK NY |
| Township / Civil Division | ISLIP |
| Census Block Group | 1 |
| Census Block | 1000 |
| Census Tract | 147504 |
21 William Ave is owned and occupied by an individual who bought it in September 2005.
Source: Suffolk County and Islip Town records, as of August 11, 2026
| Owner of Record | Individual Name on File |
|---|---|
| Mailing Address | 21 WILLIAM AVE, EAST ISLIP, NY 11730-2304 |
| Occupancy | Owner Occupied |
| Owner Type | Individual |
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 | Name on Deed |
|---|---|
| Last Sale | Sep 16, 2005 · Amount on File |
| Deed Sale | Sep 16, 2005 · Amount on File |
| Deed Book / Page | 12409 / 676 |
| Record Updated | Sep 20, 2026 |
Source: Suffolk County and Islip Town assessment roll, as of August 11, 2026
| Type | Name |
|---|---|
| State | New York |
| County | Suffolk County |
| County Subdivision | Islip Town |
| Unified School District | East Islip Union Free School District (PK - 12) |
| Year | Tax Bill | Assessed Value | Assessed Market Value |
|---|---|---|---|
| 2025 | $31,000 Land $9,900 Building $21,100 | $436,620 (-) Land $139,437 Building $297,183 | |
| 2024 | $8,348.00 | $436,620 (+2.54%) Land $139,437 Building $297,183 | |
| 2023 | $31,000 Land $9,900 Building $21,100 | $425,824 Land $135,989 Building $289,835 |
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 21 William Ave in Zone X, an area of minimal flood risk, though there have been 1 flood claim nearby since 2005.
Source: FEMA National Flood Hazard Layer, effective September 18, 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 |
| Flood Insurance Cost | Premium on File median of 14 policies |
| Nearby Flood Policies | 14 in force |
| Nearby Flood Claims | 1 (2005) |
| Claims Outside the SFHA | 1 of 1 |
| Most Recent Claim | Oct 2005 · rainfall accumulation |
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.
Wildfire risk around 21 William Ave is low, with less than a 0.01% annual chance of wildfire.
Source: USDA Forest Service Wildfire Risk to Communities (2nd edition), as of 2024
| Wildfire Risk | Low lower than 96% of the US · lower than 95% of New York |
|---|---|
| Wildfire Likelihood | Under 0.01% annual chance |
| Exposure | None beyond 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 | SUFFOLK COUNTY WATER AUTHORITY serves 1,100,000 people · EPA ID NY5110526 |
|---|---|
| Water Source | Groundwater |
| Last State Inspection | Jan 2024 |
| Lead | 1 ppb (2025–2027) action level 15 ppb |
| Water Quality | Asbestos resolved · Jul 2020 |
|---|---|
| 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 358 locations within half a mile, as of December 31, 2025
| Provider | Max Down / Up (Mbps) |
|---|---|
| Optimum Fiber · Cable | 8,000 / 8,000 |
| Verizon Fiber | 2,300 / 2,300 |
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