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Arsenic in Private Wells

Summary Indicator Report Data View Options

Arsenic in Private Wells by County, New Jersey, 2002-2022

Why Is This Important?

Arsenic is a naturally-occurring element in the earth's crust, and trace amounts can be found in geologic formations and aquifers in parts of New Jersey. Arsenic may also be found in soils as a result of past use of arsenic-containing pesticides and wood preservatives. Arsenic has been classified by the U.S. Environmental Protection Agency (USEPA) as a known human carcinogen. Ingestion of large amounts of inorganic arsenic is associated with increased risk of several types of cancer, including skin, lung, liver, kidney and urinary bladder. Other potential effects of ingesting large amounts of arsenic include diarrhea, thickening and/or discoloration of the skin, diabetes, and heart disease.


Percent of tested private wells with arsenic concentration exceeding the maximum contaminant level (MCL) of 5 micrograms of arsenic per liter

Data Source

Private Well Testing Act Data, Division of Water Supply and Geoscience, New Jersey Department of Environmental Protection

How the Measure is Calculated

Numerator:Number of tested private wells with arsenic concentration exceeding the maximum contaminant level of 5 micrograms of arsenic per liter in a specified period of time
Denominator:Number of tested private wells in a specified period of time

How Are We Doing?

Between 2002 and 2022, about 6% of 80,560 private wells in New Jersey that were tested for arsenic exceeded the state maximum contaminant level (MCL) of 5 micrograms per liter. Arsenic standard exceedances were most commonly found in Essex, Hunterdon, Mercer, and Somerset Counties. Online maps showing detection of arsenic are available at the county level, municipal level, and for 2 mile by 2 mile grids from NJDEP, [].

What Is Being Done?

The New Jersey Department of Environmental Protection (NJDEP) adopted a new maximum contaminant level (MCL) for arsenic of 5 micrograms per liter, effective in January 2006, giving New Jersey the most protective arsenic standard in the nation. The MCL for arsenic in the U.S. is 10 micrograms per liter. The New Jersey Private Well Testing Act (PWTA) became effective in September 2002. The PWTA requires the buyer or the seller of real property to test well water prior to sale and review the results prior to closing of title. It also requires landlords to test the private well water supplied to their tenants and provide their tenants with a written copy of the results. Test results are provided to homeowners by the laboratory performing the analyses and are also sent to the New Jersey Department of Environmental Protection (NJDEP). The NJDEP notifies the local health agency when a well within its jurisdiction is tested under the PWTA. The data from the PWTA are used by NJDEP to assess the quality of the water from private wells throughout the state. Arsenic was initially required to be tested for in private wells in only 12 of New Jersey's 21 counties. These counties were selected due to the higher likelihood of finding arsenic. Testing for arsenic was added in two counties (Sussex and Warren) beginning in March 2008 and testing for arsenic is now required in all NJ counties.

Available Services

If your drinking water comes from a private well, you are responsible for testing. The NJDEP recommends that you use a laboratory that is NJDEP-certified. You can call the NJDEP Office of Quality Assurance at (609) 292-3950 for information on laboratories certified to test drinking water or look for the information online at: [] using the "Search by Category" option, select "Certified Laboratories", and search for "Certified Drinking Water Labs", "PWTA Laboratories Certified for Sampling", or "Laboratories Certified by Parameter". Testing is required for sale of residential real estate when a private well is the source of drinking water. For more information, contact the NJDEP Private Well Testing Program at (866) 479-8378 or visit: [] Private Well Testing Act Frequently Asked Questions: [] NJ Private Well Testing Act Data Summary, by county, municipality, and 2 mile by 2 mile grid: [] NJDOH Drinking Water Facts: Private Wells, [] NJDOH Drinking Water and Public Health Project, [] To inquire about New Jersey well permitting and regulation, contact the NJDEP Division of Water Supply at (609) 984-6831. For information on federal drinking water regulations, and other water safety issues, contact the United States Environmental Protection Agency Safe Drinking Water Hotline at (800) 426-4791.

More Resources

Although short-term exposures to high doses of arsenic can cause adverse effects in people, such exposures do not typically occur from private wells in New Jersey. Some people who drink water containing arsenic well in excess of the maximum contaminant level could experience skin damage or problems with the circulatory system, and may have an increased risk of certain cancers. U.S. EPA's guide to drinking water from household wells: []

Indicator Data Last Updated On 05/11/2023, Published on 05/11/2023
Environmental Public Health Tracking Project, New Jersey Department of Health, PO Box 369, Trenton, NJ 08625-0369, e-mail: (