Nassau County, New York
108 ZIP codes · Avg score 76/100 · Grade B · Updated 2026-06-04
Covering 108 ZIP codes, Nassau County earns a high grade for tap water — most systems report zero health-based violations, and the overall compliance rate comfortably exceeds federal benchmarks.
How Nassau County Compares
How Nassau County Compares
Nassau County scores 15 points above the New York state average (61/100) and 8 points above the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-04
ZIP Code Risk Map
Water Quality Map: Nassau County, New York
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 10.8 (asthma 9.5%, diabetes 10.7%)
Estimated additional annual cost per homeowner: $4,999, driven primarily by sea_level
Infrastructure: 0.471% avg pipe failure probability, 90% of ZIPs at high risk
88.2% of homes built before 1978 (lead paint era)
Violation History (2023–2024)
→ Stable trendEPA violation counts by year across Nassau County water systems. Health-based shown in red, total in blue.
Peak year: 2024 with 76 violations. Past 5 years: 107 total (107 health-based).
Source: EPA SDWIS historical violations. Data may lag 6–12 months for the most recent year.
County Health Indicators vs National Average
Black markers indicate national averages. Source: CDC PLACES, Census ACS.
Infrastructure Overview
Sources: Census ACS (housing age), EPA SDWIS (infrastructure risk model), state bridge inspection data.
Compound Risk Breakdown
Estimated additional annual cost per homeowner: $4,999
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
557,475 housing units in Nassau County
Source: U.S. Census Bureau ACS B25034 (Year Structure Built).
Water Safety Affordability
How much it costs to fix water issues relative to home values in Nassau County
Remediation costs are relatively manageable for most homeowners in Nassau County, representing a small fraction of property value.
Remediation includes water filtration, lead abatement, radon mitigation, and flood protection where applicable. Source: Census ACS, EPA SDWIS.
Health Outcomes vs National Average
CDC PLACES data for Nassau County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water Systems with Most Violations
Top 5 systems in Nassau County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Town of Hempstead Water Department | 110,000 | 39 |
| 2 | MANHASSET LAKEVILLE WD | 43,000 | 37 |
| 3 | Roslyn Water District | 17,000 | 37 |
| 4 | Liberty Utilities New York - Merrick | 135,000 | 37 |
| 5 | Garden City Park Water District | 18,000 | 34 |
54 total water systems serve Nassau County.
All ZIP Codes in Nassau County
108 ZIP codes tracked in Nassau County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 11026 | Great Neck | 99 | A | 0 | — |
| 2 | 11027 | Great Neck | 99 | A | 0 | — |
| 3 | 11041 | New Hyde Park | 99 | A | 0 | — |
| 4 | 11571 | Rockville Centre | 99 | A | 0 | — |
| 5 | 11592 | Rockville Center | 99 | A | 0 | — |
| 6 | 11736 | Farmingdale | 99 | A | 0 | — |
| 7 | 11737 | Farmingdale | 99 | A | 0 | — |
| 8 | 11773 | Syosset | 99 | A | 0 | — |
| 9 | 11774 | Farmingdale | 99 | A | 0 | — |
| 10 | 11802 | Hicksville | 99 | A | 0 | — |
| 11 | 11815 | Hicksville | 99 | A | 0 | — |
| 12 | 11819 | Hicksville | 99 | A | 0 | — |
| 13 | 11854 | Hicksville | 99 | A | 0 | — |
| 14 | 11855 | Hicksville | 99 | A | 0 | — |
| 15 | 11022 | Great Neck | 95 | A | 0 | — |
| 16 | 11547 | Glenwood Landing | 95 | A | 0 | $917K |
| 17 | 11549 | Hempstead | 92 | A | 8 (3 health) | — |
| 18 | 11551 | Hempstead | 92 | A | 8 (3 health) | — |
| 19 | 11020 | Great Neck | 90 | A | 0 | $1156K |
| 20 | 11501 | Mineola | 90 | A | 0 | $627K |
| 21 | 11514 | Carle Place | 90 | A | 0 | $714K |
| 22 | 11552 | West Hempstead | 90 | A | 1 | $616K |
| 23 | 11579 | Sea Cliff | 90 | A | 0 | $927K |
| 24 | 11590 | Westbury | 90 | A | 1 | $617K |
| 25 | 11596 | Williston Park | 90 | A | 0 | $802K |
| 26 | 11735 | Farmingdale | 90 | A | 0 | $572K |
| 27 | 11791 | Syosset | 90 | A | 0 | $919K |
| 28 | 11801 | Hicksville | 90 | A | 0 | $611K |
| 29 | 11568 | Old Westbury | 89 | A | 1 | $2000K |
| 30 | 11010 | Franklin Square | 88 | A | 1 | $647K |
| 31 | 11021 | Great Neck | 85 | A | 0 | $734K |
| 32 | 11023 | Great Neck | 85 | A | 0 | $1144K |
| 33 | 11024 | Great Neck | 85 | A | 0 | $1634K |
| 34 | 11030 | Manhasset | 85 | A | 1 | $1801K |
| 35 | 11542 | Glen Cove | 85 | A | 0 | $659K |
| 36 | 11554 | East Meadow | 85 | A | 0 | $614K |
| 37 | 11560 | Locust Valley | 85 | A | 0 | $938K |
| 38 | 11570 | Rockville Centre | 85 | A | 0 | $787K |
| 39 | 11576 | Roslyn | 85 | A | 0 | $1215K |
| 40 | 11771 | Oyster Bay | 85 | A | 0 | $921K |
| 41 | 11803 | Plainview | 85 | A | 0 | $732K |
| 42 | 11051 | Port Washington | 84 | B | 3 (3 health) | — |
| 43 | 11053 | Port Washington | 84 | B | 3 (3 health) | — |
| 44 | 11055 | Port Washington | 84 | B | 3 (3 health) | — |
| 45 | 11550 | Hempstead | 84 | B | 8 (3 health) | $447K |
| 46 | 11714 | Bethpage | 82 | B | 0 | $586K |
| 47 | 11797 | Woodbury | 77 | B | 6 | $1006K |
| 48 | 11577 | Roslyn Heights | 76 | B | 33 | $945K |
| 49 | 11520 | Freeport | 75 | B | 0 | $481K |
| 50 | 11561 | Long Beach | 75 | B | 1 | $677K |
| 51 | 11709 | Bayville | 75 | B | 1 | $671K |
| 52 | 11510 | Baldwin | 74 | B | 3 | $579K |
| 53 | 11001 | Floral Park | 73 | B | 0 | $715K |
| 54 | 11004 | Glen Oaks | 73 | B | 0 | $662K |
| 55 | 11426 | Bellerose | 73 | B | 0 | $676K |
| 56 | 11428 | Queens Village | 73 | B | 0 | $666K |
| 57 | 11429 | Queens Village | 73 | B | 0 | $646K |
| 58 | 11548 | Greenvale | 73 | B | 0 | $701K |
| 59 | 11556 | Uniondale | 73 | B | 0 | — |
| 60 | 11565 | Malverne | 73 | B | 0 | $629K |
| 61 | 11690 | Far Rockaway | 73 | B | 0 | — |
| 62 | 11732 | East Norwich | 73 | B | 0 | $753K |
| 63 | 11765 | Mill Neck | 73 | B | 0 | $2000K |
| 64 | 11535 | Garden City | 70 | B | 1 | — |
| 65 | 11050 | Port Washington | 68 | C | 3 (3 health) | $991K |
| 66 | 11758 | Massapequa | 67 | C | 0 | $625K |
| 67 | 11002 | Floral Park | 66 | C | 0 | — |
| 68 | 11005 | Floral Park | 66 | C | 0 | $620K |
| 69 | 11359 | Bayside | 66 | C | 0 | — |
| 70 | 11531 | Garden City | 66 | C | 1 | — |
| 71 | 11555 | Uniondale | 66 | C | 0 | — |
| 72 | 11582 | Valley Stream | 66 | C | 0 | — |
| 73 | 11599 | Garden City | 66 | C | 1 | — |
| 74 | 11853 | Jericho | 66 | C | 0 | — |
| 75 | 11003 | Elmont | 65 | C | 0 | $577K |
| 76 | 11411 | Cambria Heights | 65 | C | 0 | $622K |
| 77 | 11507 | Albertson | 65 | C | 0 | $800K |
| 78 | 11530 | Garden City | 65 | C | 1 | $988K |
| 79 | 11545 | Glen Head | 65 | C | 0 | $1029K |
| 80 | 11553 | Uniondale | 65 | C | 0 | $486K |
| 81 | 11563 | Lynbrook | 65 | C | 0 | $596K |
| 82 | 11575 | Roosevelt | 65 | C | 0 | $457K |
| 83 | 11753 | Jericho | 65 | C | 0 | $950K |
| 84 | 11756 | Levittown | 65 | C | 0 | $557K |
| 85 | 11798 | Wyandanch | 65 | C | 0 | — |
| 86 | 11804 | Old Bethpage | 65 | C | 0 | $773K |
| 87 | 11566 | Merrick | 63 | C | 13 (6 health) | $679K |
| 88 | 11362 | Little Neck | 60 | C | 0 | $635K |
| 89 | 11363 | Little Neck | 60 | C | 0 | $1019K |
| 90 | 11413 | Springfield Gardens | 60 | C | 0 | $632K |
| 91 | 11580 | Valley Stream | 60 | C | 0 | $603K |
| 92 | 11710 | Bellmore | 58 | C | 0 | $647K |
| 93 | 10464 | Bronx | 55 | C | 0 | $668K |
| 94 | 11096 | Inwood | 55 | C | 0 | $605K |
| 95 | 11422 | Rosedale | 55 | C | 0 | $629K |
| 96 | 11516 | Cedarhurst | 55 | C | 0 | $819K |
| 97 | 11557 | Hewlett | 55 | C | 0 | $708K |
| 98 | 11559 | Lawrence | 55 | C | 0 | $1108K |
| 99 | 11569 | Point Lookout | 55 | C | 0 | $1049K |
| 100 | 11762 | Massapequa Park | 55 | C | 0 | $623K |
| 101 | 11509 | Atlantic Beach | 50 | D | 0 | $991K |
| 102 | 11518 | East Rockaway | 50 | D | 0 | $591K |
| 103 | 11558 | Island Park | 50 | D | 0 | $602K |
| 104 | 11572 | Oceanside | 50 | D | 0 | $627K |
| 105 | 11581 | Valley Stream | 50 | D | 0 | $653K |
| 106 | 11598 | Woodmere | 50 | D | 0 | $1000K |
| 107 | 11691 | Far Rockaway | 50 | D | 0 | $649K |
| 108 | 11783 | Seaford | 50 | D | 0 | $627K |
Recommended Buyer Guides for Nassau County
Where county records show a lead exceedance or pre-1978 housing concentration, lead-specific filters and test kits move toward the top of the list.
- Best Water Filters for Lead — Lead above EPA action level in 4 ZIP codes
- Best Lead Paint Test Kits — 88.2% of homes built before 1978
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
Deep Dive Reports
Detailed analysis for Nassau County, New York
Overview
Nassau County in New York covers 108 ZIP codes with an average Home Safety Score of B (76/100).
22 of 108 ZIP codes have recorded EPA violations. 27 health-based violations have been documented.
← Back to New York water quality report
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Home values: U.S. Census Bureau ACS (median estimates by ZCTA)
Updated daily.