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Manganese 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

Manganese is widespread, over the limit in 15% or more of tested wells, in 6 of the 17 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 manganese test See every county

How New Jersey compares with the rest of the country

Across New Jersey, about 1 in 8 tested wells had manganese over the EPA health advisory of 0.3 mg/L (102 of 824). Across all tested wells in the US it's about 1 in 7. New Jersey is about average, so the county you live in tells you more than the state does.

Why it matters: High levels over many years may affect the nervous system, and babies are more sensitive to it. It also leaves black stains.

Manganese dissolves out of rock and soil, especially in water with little oxygen.

Manganese in tested wells, county by county

Share of each county's tested wells with at least one result over the EPA health advisory of 0.3 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
Middlesex County 51
33% 17 of 51
 Widespread
Monmouth County 51
22% 11 of 51
 Widespread
Mercer County 33
21% 7 of 33
 Widespread
Somerset County 10
20% 2 of 10
 Widespread
Bergen County 12
17% 2 of 12
 Widespread
Camden County 70
16% 11 of 70
 Widespread
Salem County 47
15% 7 of 47
 Worth checking
Burlington County 54
13% 7 of 54
 Worth checking
Morris County 32
12% 4 of 32
 Worth checking
Cape May County 60
10% 6 of 60
 Worth checking
Warren County 23
9% 2 of 23
 Worth checking
Hunterdon County 38
8% 3 of 38
 Worth checking
Gloucester County 94
7% 7 of 94
 Worth checking
Cumberland County 73
7% 5 of 73
 Worth checking
Atlantic County 45
2% 1 of 45
 Rare
Ocean County 70
0% 0 of 70
 Rare
Sussex County 35
0% 0 of 35
 Rare

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

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

Where to get your well tested for manganese 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 manganese.

Compare kits

Keep reading about wells in New Jersey

Questions people ask about manganese in New Jersey

Is there manganese in New Jersey well water?

Manganese is widespread, over the limit in 15% or more of tested wells, in 6 of the 17 New Jersey counties with 10 or more tested wells. Across New Jersey, about 1 in 8 tested wells had manganese over the EPA health advisory of 0.3 mg/L (102 of 824). Across all tested wells in the US it's about 1 in 7. 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 manganese in New Jersey?

Use a lab certified by New Jersey for drinking water, or a mail-in kit that includes manganese 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 health advisory of 0.3 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.