Tested Water
Menu

Nitrate 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

Nitrate is widespread, over the limit in 15% or more of tested wells, in 2 of the 16 New Jersey counties with 10 or more tested wells. 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 nitrate test See every county

How New Jersey compares with the rest of the country

Across New Jersey, about 1 in 13 tested wells had nitrate over the EPA limit of 10 mg/L (52 of 660). Across all tested wells in the US it's about 1 in 12. New Jersey is about average, so the county you live in tells you more than the state does.

Why it matters: It's dangerous for babies under 6 months, because it keeps their blood from carrying enough oxygen.

Nitrate soaks down into groundwater from fertilizer, manure and septic systems.

Nitrate in tested wells, county by county

Share of each county's tested wells with at least one result over the EPA limit of 10 mg/L. 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
Salem County 25
44% 11 of 25
 Widespread
Cumberland County 72
17% 12 of 72
 Widespread
Warren County 23
13% 3 of 23
 Worth checking
Somerset County 10
10% 1 of 10
 Worth checking
Atlantic County 41
10% 4 of 41
 Worth checking
Burlington County 48
8% 4 of 48
 Worth checking
Middlesex County 40
8% 3 of 40
 Worth checking
Gloucester County 77
6% 5 of 77
 Worth checking
Mercer County 31
6% 2 of 31
 Worth checking
Sussex County 35
6% 2 of 35
 Worth checking
Monmouth County 37
5% 2 of 37
 Worth checking
Camden County 50
4% 2 of 50
 Rare
Ocean County 53
0% 0 of 53
 Rare
Hunterdon County 37
0% 0 of 37
 Rare
Morris County 31
0% 0 of 31
 Rare
Bergen County 16
0% 0 of 16
 Rare

5 more New Jersey counties have 1 to 9 tested wells for nitrate, too few to rate.

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

Where to get your well tested for nitrate 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 nitrate.

Compare kits

Keep reading about wells in New Jersey

Questions people ask about nitrate in New Jersey

Is there nitrate in New Jersey well water?

Nitrate is widespread, over the limit in 15% or more of tested wells, in 2 of the 16 New Jersey counties with 10 or more tested wells. Across New Jersey, about 1 in 13 tested wells had nitrate over the EPA limit of 10 mg/L (52 of 660). Across all tested wells in the US it's about 1 in 12. New Jersey is about average, so the county you live in tells you more than the state does.

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

Use a lab certified by New Jersey for drinking water, or a mail-in kit that includes nitrate 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 the EPA limit of 10 mg/L. 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.