Radon and home risks by county

Radon in New York

34 of New York's 62 counties are in EPA's highest radon zone, home to about 23% of the state's residents. Radon zones describe an area's potential; EPA recommends testing every home regardless of zone.

Zone 1 counties
34
high radon potential
Zone 2 counties
13
moderate potential
Zone 3 counties
15
low potential
Counties with water violations
36
since 2016; 4 with unresolved ones

Tap water reports for New York cities

New York8,478,072 residents · PFAS, lead, violations

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Zone 1: high potential (34 counties)

CountyResidentsWater systemsHealth violations since 2016Unresolved
Albany County319,9643540
Allegany County47,2992370
Broome County196,3976321
Cattaraugus County75,4755120
Cayuga County74,5673200
Chautauqua County124,1055500
Chemung County81,1152400
Chenango County45,7762900
Columbia County60,2995010
Cortland County45,9452500
Delaware County44,1913400
Dutchess County299,96315280
Erie County950,6024410
Genesee County57,6041600
Greene County46,90336200
Livingston County61,5612820
Madison County67,0722220
Onondaga County469,8122520
Ontario County113,0123500
Orange County411,767138222
Otsego County60,5243720
Putnam County98,40910100
Rensselaer County160,7493800
Schoharie County30,1511620
Schuyler County17,1211100
Seneca County32,6502600
Steuben County92,0155640
Sullivan County80,4506900
Tioga County47,5743300
Tompkins County105,6025100
Ulster County182,97711231
Washington County59,83921150
Wyoming County39,5882300
Yates County24,3871200

Zone 2: moderate potential (13 counties)

CountyResidentsWater systemsHealth violations since 2016Unresolved
Clinton County77,8713910
Jefferson County113,14057110
Lewis County26,5701500
Monroe County752,202500
Montgomery County49,6481810
Niagara County209,5702100
Oneida County228,3474570
Orleans County39,6862200
Oswego County118,3054210
Saratoga County240,3607490
Schenectady County162,26111200
St. Lawrence County106,1984000
Wayne County90,7571900

Zone 3: low potential (15 counties)

CountyResidentsWater systemsHealth violations since 2016Unresolved
Bronx County1,384,724110
Essex County36,74433100
Franklin County47,0861470
Fulton County52,0732520
Hamilton County5,082700
Herkimer County59,58535242
Kings County2,617,631110
Nassau County1,392,4384060
New York County1,660,664110
Queens County2,316,841110
Richmond County498,212110
Rockland County348,1441910
Suffolk County1,535,9092600
Warren County65,2882400
Westchester County1,006,4479260

How to read this table

Water systems counts community systems that list the county in their service area; one system can serve several counties. Health violations are breaches of a legal limit or treatment rule recorded by EPA since January 2016, not paperwork lapses. A violation stays unresolved until the state records it as fixed.

Other states

Sources: EPA Map of Radon Zones, EPA ECHO Safe Drinking Water Act data (2026Q3, published October 2026), US Census Bureau Vintage 2024 estimates. See the methodology.