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Radon in New Jersey well water, by county

By the Tested Water teamLab data from the USGS and EPA Water Quality Portal, 2000 to 2023Updated November 8, 2026

Radon is widespread, over the limit in 15% or more of tested wells, in 1 of the 8 New Jersey counties with 10 or more tested wells. 1 more look high, but those results likely overstate it. A county's share tells you how likely a problem is nearby. Only a test of your own well tells you what's in it.

Find a radon in water test See every county

How New Jersey compares with the rest of the country

Across New Jersey, about 1 in 9 tested wells had radon in water over 4,000 pCi/L, a level the EPA proposed (22 of 204). Across all tested wells in the US it's about 1 in 24. So radon in water turns up in New Jersey wells about 3 times as often as in the country as a whole, and a test is worth adding even if your county isn't on the list below.

Why it matters: It escapes into the air when you shower or run the tap, and breathing it raises the risk of lung cancer.

Radon is a gas given off by uranium in granite and similar rock.

Radon in tested wells, county by county

Share of each county's tested wells with at least one result over 4,000 pCi/L, a level the EPA proposed. Counties need 10 or more tested wells to be listed. Widespread means 15% or more, worth checking 5 to 15%, rare under 5%.

CountyWells testedWells over the limitLevel
Hunterdon County 13
54%* 7 of 13
 Widespread
Sussex County 23
35% 8 of 23
 Widespread
Gloucester County 31
0% 0 of 31
 Rare
Cumberland County 27
0% 0 of 27
 Rare
Camden County 19
0% 0 of 19
 Rare
Burlington County 16
0% 0 of 16
 Rare
Ocean County 14
0% 0 of 14
 Rare
Atlantic County 11
0% 0 of 11
 Rare

* Likely overstated. These shares come from a narrow set of wells, so they probably run high for the county as a whole:

  • Hunterdon County: All of these tests come from the US Geological Survey between 2006 and 2011, so this likely overstates it.

8 more New Jersey counties have 1 to 9 tested wells for radon in water, too few to rate.

Download this table (CSV) ยท Free to reuse under CC BY 4.0

Where to get your well tested for radon in water in New Jersey

1

Your county health department

New Jersey doesn't run a statewide free testing program that we know of. Some county health departments test wells or sell kits, so call yours first.

New Jersey's private well page
3

A mail-in kit

Fill the bottles at your kitchen tap and mail them back. We mark the kits that include radon in water.

Compare kits

Keep reading about wells in New Jersey

Questions people ask about radon in water in New Jersey

Is there radon in water in New Jersey well water?

Radon is widespread, over the limit in 15% or more of tested wells, in 1 of the 8 New Jersey counties with 10 or more tested wells. 1 more look high, but those results likely overstate it. Across New Jersey, about 1 in 9 tested wells had radon in water over 4,000 pCi/L, a level the EPA proposed (22 of 204). Across all tested wells in the US it's about 1 in 24. So radon in water turns up in New Jersey wells about 3 times as often as in the country as a whole, and a test is worth adding even if your county isn't on the list below.

Where can I get my well tested for radon in water in New Jersey?

Use a lab certified by New Jersey for drinking water, or a mail-in kit that includes radon in water from a certified lab. Some county health departments test wells too, so call yours first.

See New Jersey's list of certified labs, or compare mail-in kits.

Where these numbers come from

  • Lab tests: Water Quality Portal (USGS and EPA), well samples since 2000. A well counts as over if any of its tests was over 4,000 pCi/L, a level the EPA proposed. Wells tested for studies and monitoring, not a random sample of homes.
  • Likely overstated: our own check of who tested the wells, when and where. How we check.
  • State programs and links: Department of Environmental Protection.