Well water testing in Hunterdon County, New Jersey

Last verified: 2026-10-28 · 27 sources · What we couldn't verify

Arsenic is the big one in Hunterdon County wells: 15.7% of 13,700 wells tested under New Jersey's Private Well Testing Act (2002-2024) were over the state's 5 µg/L limit, with the highest rates in Frenchtown, Kingwood and East Amwell. About 23% had coliform bacteria. Raritan Headwaters sells low-cost test kits at its Flemington office, and Garden State Laboratories takes samples at a Glen Gardner drop-off.

NJDEP says about 12% of New Jersey residents, roughly 1.1 million people, rely on a private well for drinking water. Raritan Headwaters, the watershed group that runs community well testing in Hunterdon County, says 80% of the households in its region depend on private wells. Hunterdon also has more Private Well Testing Act arsenic results than any other New Jersey county (13,700 wells tested from September 2002 to December 2024). Outside of a sale or lease, New Jersey doesn't require you to test your well.^{[7][14][1][4]}

Free and low-cost testing programs

Labs that serve the county

NJDEP certifies labs test by test, and certified labs are not located in every county; you may use any NJ-certified drinking water lab, in or out of state. For a PWTA test you only need to contact one lab, which subcontracts any tests it can't do and files the results with NJDEP. The 48-hour rapid gross alpha test is done at few labs (NJDEP says most are out of state), so NJ labs usually collect and ship that sample. Raritan Headwaters is a testing program, not a lab, and its results are for your information only. Certification questions: NJDEP Office of Quality Assurance, 609-292-3950, oqa@dep.nj.gov.^{[8][9][6][19]}

Local contaminants of concern

• Major concern Arsenic. 15.7% of 13,700 Hunterdon wells tested under the PWTA (September 2002-December 2024) were over New Jersey's 5 µg/L arsenic limit, the third-highest share among NJ counties after Mercer (17.9%) and Somerset (16.2%). Rates vary sharply by town: Frenchtown 67.4% (46 wells), Kingwood 43%, East Amwell 42.5%, Alexandria 23.5%, Raritan 22.2% (2,269 wells), Delaware 21.7%, Readington 19.1% and West Amwell 17.2%, versus Lebanon Township 0.6%, Bethlehem 0.4%, Tewksbury 1.8% and Clinton Township 3.6%. NJDEP calls the Piedmont region the state's highest-risk area for arsenic (about 17% of its wells over the limit) and says the arsenic is mostly naturally occurring. You can't see, smell or taste it.^[1][2][5]
• Moderate concern Coliform bacteria / E. coli. Total coliform bacteria were present in 23.1% of Hunterdon wells tested under the PWTA, and fecal coliform or E. coli in 3.3% (about 13,700 wells, 2002-2024). Town rates for total coliform ran from about 17-18% (Frenchtown, Tewksbury) to 35% in Franklin Township and 40.5% in Califon (37 wells). Coliform is a sign that surface water or septic seepage may be reaching the well; NJDEP and the county recommend a bacteria test every year.^{[1][2][3][13]}
• Moderate concern Gross alpha (radium, uranium). 5.8% of 12,490 Hunterdon wells were over the 15 pCi/L gross alpha standard. The highest town rates were West Amwell 16.6%, Kingwood 13%, Delaware Township 11.7% and Raritan Township 11.2%. Uranium itself was over its 30 µg/L standard in only 0.5% of 3,783 wells; Hunterdon is one of 12 counties where the PWTA requires a uranium test. NJDEP says gross alpha comes from naturally occurring radium, uranium and radon and recommends testing at least once.^[1][2][6][3]
• Moderate concern PFAS (PFOA, PFOS, PFNA). 4.4% of 1,905 Hunterdon wells tested exceeded New Jersey's limit for at least one of the three PFAS in the PWTA (PFOA 3%, PFOS 2.5%, PFNA 0.3%). Rates were higher in West Amwell (17.3% of 52 wells) and East Amwell (10.7% of 84 wells); PFAS testing under the PWTA is recent, so sample counts are small. NJDEP recommends PFAS testing at least every five years.^[1][2][3]
• Moderate concern Iron, manganese and low pH. 16% of Hunterdon wells exceeded the 0.3 mg/L iron standard and 10.9% the 0.05 mg/L manganese standard, and 28.1% had pH outside the recommended range. Iron and manganese standards are mainly about staining and taste, but the county warns that acidic water (pH below 6.5) can corrode pipes and leach lead from soldered joints.^[1][13][3]
• Lower concern Nitrate. Only 0.8% of Hunterdon wells were over the 10 mg/L nitrate limit; no town with at least 50 wells tested topped 2%.^[1][2]
• Lower concern VOCs and synthetic organic compounds. 0.5% of wells exceeded a limit for at least one volatile organic compound (13,703 wells) and 0.5% for a synthetic organic compound such as 1,2,3-TCP (3,808 wells). Raritan Headwaters says it can tell you about local SOC hot spots in NJDEP data.^[1][15]

These figures come from NJDEP's summary of Private Well Testing Act results, September 2002-December 2024. They are tests of untreated water from homes being sold or rented, not a random sample, and town figures based on a few dozen wells are less reliable. NJDEP says about a quarter of the state's wells have been tested under the Act.

A county rate can't tell you what's in your well. Only a test can. See what to test for.

Typical cost

Prices are from the published lists cited, as of the last-verified date. Confirm before ordering.

How often to test

• Every year: total coliform bacteria, nitrate and pH (NJ Department of Health recommendation, via NJDEP). Hunterdon County's health department also recommends a yearly bacteria test.^[3][13]
• Every five years: PFAS, lead, VOCs, synthetic organic compounds, iron and manganese. At least once: arsenic, mercury, gross alpha and uranium.^[3][4]
• Arsenic: if your last result was above 2.5 µg/L, test every year; below 2.5 µg/L, at least every five years. If you have arsenic treatment, test the treated water after installation and every year.^[5]
• Also test when the water changes color, odor or taste, a child or pregnant person lives in the house, after a flood, fire or chemical spill near the well, whenever the well cap is removed, or when neighbors have water problems. A full PWTA test is required when you sell, and landlords must repeat it every five years.^[3][4]

How to collect a sample

General rules from NJDEP and Garden State Laboratories. Always follow your own lab's or Raritan Headwaters' kit instructions:

1. Get bottles from the lab or program and use only those. Don't rinse them (bacteria bottles contain a preservative) and don't touch the inside of the bottle, the rim or the cap.
2. Use a cold-water tap, ideally one with separate hot and cold handles and not a swivel faucet. Remove the aerator, screen or any attachment and disinfect the tap opening with an alcohol wipe or spray.
3. To test your raw well water, sample before any treatment system (or bypass it), and let the water run first: a few minutes for bacteria, longer for a PWTA sample depending on the pressure tank size.
4. Fill the bacteria bottle at a moderate stream to the marked line, label it and fill out the chain-of-custody form (name, address, date and time, tests wanted).
5. Keep samples cold (ice packs, in a plastic bag) and get them to the lab or its pick-up location the same day you sample; total coliform analysis must start within 30 hours. For Raritan Headwaters events, return samples at the posted drop-off time.
6. For a home sale, you can't collect the sample yourself: a certified lab employee or authorized representative must collect it, and pH must be measured by the lab. Gross alpha must be analyzed within 48 hours.

Source^{[23][4][18][6]}. General steps: How to test your well water.

After you get results

Your lab report compares results with state and federal standards. If arsenic is over 5 µg/L, NJDEP recommends bottled water for drinking and cooking until you install treatment, ideally a whole-house system; boiling doesn't remove arsenic and simple carbon filters don't either. If gross alpha is over 15 pCi/L, test for uranium, radium-226/228 and radon before choosing treatment (5-15 pCi/L: test for radium). Retest after any treatment is installed. NJHMFA offers 0% treatment loans (see programs), and the county health department (908-788-1351) can answer questions.^{[3][5][6][10]}

What we couldn't verify

• Current NJDEP certification of each listed lab: NJDEP's real-time DataMiner lab lists would not load for us, so Garden State Labs' (#20044) and RAdata's (#14006) certifications come from their own websites, and All-State and ALS from Hillsborough Township's list and ALS's site.
• All-State Well Testing Services' services, prices, homeowner testing and certification (its website returned a server error).
• Whether any listed lab accepts mailed-in well samples from Hunterdon homeowners (only RAdata's radon-in-water kits are described as shipped back).
• Garden State Labs' prices other than total coliform, and how current that price sheet is; its PWTA test price.
• ALS Toms River prices and its homeowner kit options for New Jersey wells; what RAdata's 'starting at $950' price covers.
• Which certified lab analyzes Raritan Headwaters samples, and its spring 2027 event dates.
• Any free or subsidized well testing from Hunterdon County, its towns or Rutgers Cooperative Extension of Hunterdon County; we found none.
• A Hunterdon County radon-in-water rate; we found no published county figure.

Sources

1. NJDEP (Open Data): Private Well Testing Act Summary Results by County for New Jersey (Sept. 2002-Dec. 2024)
2. NJDEP (Open Data): Private Well Testing Act Summary Results by Municipality for New Jersey (Sept. 2002-Dec. 2024)
3. NJDEP: Private Wells: Well Testing (what and how often to test, treatment help)
4. NJDEP: New Jersey Private Well Testing Act (PWTA) FAQs
5. NJDEP: Arsenic in Private Well Water
6. NJDEP: Gross Alpha Radioactivity
7. NJDEP: Private Well Basics
8. NJDEP Office of Quality Assurance: Private Well Testing Act (PWTA): sampling, testing and certified labs
9. NJDEP Office of Quality Assurance: Certified Laboratories (real-time lists)
10. Hunterdon County Department of Health: Safe Drinking Water Program
11. Hunterdon County Department of Health: Environmental Health Services
12. Hunterdon County: Septic and Well Records
13. Hunterdon County Health Department: Our Most Valuable Resource: Well & Septic Care Guide (PDF)
14. Raritan Headwaters: Well Testing (testing options and fees)
15. Raritan Headwaters: What Should I Test My Well Water For? (menu of testing options, July 2026, PDF)
16. Raritan Headwaters: Community Well Testing
17. Raritan Headwaters: Community Well Testing events (2026)
18. Raritan Headwaters: Kingwood Township Community Well Testing (Oct. 31 and Nov. 2, 2026)
19. Hillsborough Township Health and Environmental Services: Certified Water Testing Laboratories/Water Testing Entities (PDF)
20. Garden State Laboratories: Locations (labs and drop-off offices)
21. Garden State Laboratories: Accreditation and Certifications
22. Garden State Laboratories: Drinking Water Testing (homeowner and PWTA)
23. Garden State Laboratories: Bacteria (Coliform and Heterotrophic Plate Count) Sampling Procedure (PDF)
24. Garden State Laboratories: PWTA (Private Well Testing Act services)
25. RAdata: New Jersey Home Water Testing Services
26. RAdata: Professional Water Testing (radon in water kits)
27. ALS: Drinking water testing

All sources accessed on or before 2026-10-28.

More useful links

• NJDEP: Private well research and interactive PWTA maps
• Raritan Headwaters: Arsenic and Well Water

All New Jersey county guides