Well water testing in Johnston County, North Carolina

Last verified: 2026-10-31 · 19 sources · What we couldn't verify

Iron and manganese are the most common problems in Johnston County wells: in UNC's analysis of state lab results, 32.47% of 2,002 wells tested were above EPA's manganese health advisory. Johnston County Environmental Health runs a fee-based sampling service ($29 bacteria test), and the county advises radionuclide testing at a private lab in its western and northern areas.

NCDHHS says about 2.4 million North Carolinians rely on groundwater as their primary drinking water source, and that there is no mandated oversight of private well water quality, so monitoring it is the homeowner's responsibility. Every newly constructed private well in North Carolina must be tested for bacterial and chemical contaminants within 30 days of completion. In Johnston County, a new drinking water well must pass bacteriological, chemical and nitrate/nitrite samples, and be free of coliform bacteria, before Environmental Health issues a certificate of completion. Johnston County notes that if you pay a water bill, you're on public water. We found no published count of Johnston County homes on private wells.^{[9][8][1][4][3]}

Free and low-cost testing programs

Labs that serve the county

North Carolina certifies drinking-water labs for each contaminant, so check that a lab is certified for the test you need (for example, Eurofins Raleigh is certified for bacteria and nitrate but not arsenic). Johnston County's radionuclide list also names Pace Analytical Services in Raleigh (919-834-4984), saying it will collect the sample for a fee or sell you a bottle to return, but we didn't find a Pace Raleigh lab on the state's current certified drinking-water list, so confirm its certification before using it. The county's list says radionuclide results go only to the customer and aren't shared with any other agency.^[12][3]

Local contaminants of concern

• Major concern Manganese and iron. In the UNC Superfund Research Program's analysis of NCWELL data (state lab results), 650 of 2,002 Johnston County wells tested (32.47%) were above EPA's 300 µg/L manganese health advisory (maximum 3,170 µg/L), and 282 of 923 (30.55%) were above the DEQ iron level of 2,500 µg/L (maximum 25,000 µg/L). In the state lab's 1998-2010 county report, 32.65% of 1,458 wells were above the 300 µg/L iron secondary standard and 29.11% of 1,460 were above the 50 µg/L manganese secondary standard.^[5][6][7]
• Local hot spots Uranium, radium and radon. Johnston County Environmental Health says the western and northern parts of the county sit on Late Paleozoic granites and granodiorites, which can release uranium, radium and radon into groundwater, and that a certified lab test is the only way to know. A 2019 News & Observer report said the Rolesville granite behind eastern Wake County's well contamination extends into a portion of Johnston County just north of Clayton. Data are thin: the UNC/NCWELL summary has only 3 Johnston County uranium results, 1 of them above the 30 µg/L standard (maximum 110 µg/L). The county doesn't test for radionuclides, so use a private certified lab.^{[3][18][5][1]}
• Moderate concern Sodium. 838 of 840 Johnston County wells tested for sodium (99.76%) were above EPA's 20,000 µg/L sodium advisory level, which matters for people on low-sodium diets (UNC/NCWELL).^[5]
• Moderate concern Acidic water (low pH) and zinc. In the state lab's 1998-2010 county report, 564 of 1,463 wells (38.55%) had a pH below the 6.5-8.5 secondary range. Secondary standards cover cosmetic or aesthetic effects and technical effects such as damage to water fixtures. 143 of 922 wells (15.51%) were above North Carolina's 1,000 µg/L groundwater standard for zinc (UNC/NCWELL), and 18 of 1,453 (1.24%) were above the 5,000 µg/L secondary standard in the state report.^[6][5]
• Moderate concern Lead and copper. 50 of 2,003 wells tested (2.5%) were above the 15 µg/L lead action level, with a maximum of 197 µg/L, and 5 of 922 (0.54%) were above the 1,300 µg/L copper action level (UNC/NCWELL). In the state's 1998-2010 report, 2.84% of 1,480 wells were above the lead level and 1.10% of 1,461 above the copper level.^[5][6]
• Lower concern Nitrate / nitrite. 13 of 558 wells tested (2.33%) exceeded the 10,000 µg/L (10 mg/L) nitrate standard, with a maximum of 16,000 µg/L; none of 558 exceeded the nitrite standard (UNC/NCWELL). Nitrate/nitrite sampling through Johnston County is collected by the office.^[5][2]
• Lower concern Arsenic. 24 of 2,003 Johnston County wells tested (1.2%) were above the 10 µg/L arsenic standard, with a maximum of 35 µg/L (UNC/NCWELL). The state lab's 1998-2010 report found 10 of 1,460 (0.68%) above it.^[5][6]
• Not verified VOCs and petroleum. The state's 1998-2010 county report lists only 13 to 24 wells tested for individual VOCs such as benzene, MTBE, TCE and PCE, with none above standards. That is too few to judge countywide. Johnston County offers petroleum and VOC tests through Environmental Health.^[6][2]
• Not verified Bacteria. We found no countywide bacteria rate. NCDHHS recommends testing for total and fecal coliform bacteria every year, and Johnston County requires new wells to be free of coliform bacteria before it issues a certificate of completion.^[8][1]
• Not verified PFAS. We found no Johnston County private-well PFAS data in the sources reviewed, and PFAS isn't on the county's fee schedule. Some certified labs, such as GEL Laboratories, are state-certified for PFAS in drinking water. Unverified.^[2][12]

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 and fecal coliform bacteria, and check the wellhead for cracks or openings.^[8]
• Every two years: heavy metals, nitrate, nitrite, lead and copper.^[8]
• Every five years: pesticides and VOCs. Test yearly if you know a particular pesticide is used in your area.^[8]
• At least once in western and northern Johnston County: uranium, radium and radon at a private certified lab.^[3]
• New wells must be tested within 30 days of completion. Test again after well repairs or flooding.^[8]

How to collect a sample

For county tests, call Johnston County Environmental Health (919-989-5180) to choose tests; some you can collect yourself and others require a staff visit. For a mail-in kit, follow the lab's own instructions. These steps come from National Testing Laboratories' bacteria sampling instructions and the State Lab:

1. Bacteria: collect from an indoor cold-water tap. Remove the aerator or strainer and disinfect the spigot with alcohol or a flame (don't use flame if you suspect methane).
2. Run the cold water in a slow, even stream for 3-5 minutes, then fill the sterile bottle to the 100 mL line without rinsing it or touching the inside of the bottle or cap. The white crystals inside are a preservative.
3. Record the collection date and time on the lab form, ship the same day by guaranteed overnight delivery, and don't collect on Friday through Sunday or before a holiday. Bacteria samples received after 30 hours are invalid.
4. Nitrate/nitrite: keep the sample cold. The State Lab must begin analysis within 48 hours of collection.
5. Lead: collect a first-draw sample (water that has sat in the pipes).

Source^{[2][17][10][13]}. General steps: How to test your well water.

After you get results

Johnston County Environmental Health points well owners to the State Lab and EPA's drinking water standards for help interpreting results. Cameron Testing Services suggests a reverse osmosis system at the kitchen sink for failed lead or nitrate tests, and chlorinating the well and the entire plumbing system for failed bacteria tests. If radionuclides are found, retest with a certified lab before choosing treatment. Questions: Johnston County Environmental Health, 919-989-5180.^[1][13]

What we couldn't verify

• How many Johnston County homes or residents rely on private wells (no county figure found).
• Where to pick up county sample bottles and turnaround times for Johnston County Environmental Health samples (only the fee schedule and phone number are published).
• Cameron Testing Services' prices, mail-in acceptance, and whether it samples wells outside home sales (its home page returned server errors).
• Whether Eurofins Raleigh (Cary) and Eurofins Greenville accept homeowner or shipped samples, and their prices.
• Pace Analytical Services, Raleigh: named on the county's radionuclide list, but not found on the state's current certified drinking-water list; services and prices unconfirmed.
• Radionuclide test prices at GEL Laboratories, Florida Radiochemistry Services, EMSL New Jersey and Alliance Technical Group, and whether Alliance is the same business as the 'Summit Environmental Technologies' on the county list.
• Whether National Testing Laboratories' gross alpha/beta analysis is covered by its NC certification (the state lists only uranium under its radiochemistry).
• Uranium, radium and radon-in-water occurrence in Johnston County wells (only 3 uranium results in UNC/NCWELL) and the exact affected area.
• A countywide bacteria rate for private wells.
• PFAS occurrence in Johnston County private wells.
• Any free or subsidized well testing program in Johnston County (none found).
• The date range of the NCWELL data behind the UNC fact sheet, and the state's 1998-2010 report's nitrate row (it lists a 165,000 µg/L maximum but 0 wells above the standard).

Sources

1. Johnston County, NC (Environmental Health): Private Drinking Water Wells
2. Johnston County, NC: Environmental Health Fee Schedule (effective July 1, 2026)
3. Johnston County Environmental Health: Testing Private Drinking Water Wells for Radionuclides (certified lab list, PDF)
4. Johnston County: Regulations Governing Private and Semi-Public Water Supply Wells in Johnston County (PDF)
5. UNC Superfund Research Program: Well Water Contaminants in Johnston County (fact sheet, 2022; NCWELL database, Eaves et al. 2022)
6. NCDHHS Division of Public Health: Johnston County well water contaminant report (State Lab private well samples, PDF)
7. NCDHHS Division of Public Health: Well Water & Health: Contaminant Maps by County (State Lab samples 1998-2010)
8. NCDHHS Division of Public Health: Private Wells: Frequently Asked Questions about Testing
9. NCDHHS Division of Public Health: Private Wells: Facts and Figures
10. N.C. State Laboratory of Public Health: Environmental Inorganic Chemistry (private water system samples)
11. N.C. State Laboratory of Public Health: Environmental Microbiology (private well samples)
12. N.C. State Laboratory of Public Health: Certified Drinking Water Laboratories (commercial list and lab detail pages) (search form; choose "View a list of all laboratories", then click a lab name for its details)
13. Cameron Testing Services, Inc.: FHA/VA Loans: Well Test Package
14. National Testing Laboratories, Ltd.: WaterCheck Basic Well Water Test
15. National Testing Laboratories, Ltd.: WaterCheck Standard Well Water Test
16. National Testing Laboratories, Ltd.: Basic Radiological
17. National Testing Laboratories, Ltd.: Informational Bacteria Sampling Instructions (PDF)
18. The News & Observer (Raleigh): Contaminated drinking water may stretch beyond eastern Wake County private wells (June 25, 2019)
19. National Testing Laboratories, Ltd. (WaterCheck): Well Water Testing Kits

All sources accessed on or before 2026-10-31.

More useful links

• NC State Laboratory of Public Health - certified laboratory search (NC state site; it sometimes fails to connect, so try again if it does)
• Wake County: naturally occurring contamination in well water (neighboring county, Rolesville granite)

Other North Carolina counties

• Union County
• Wake County

All North Carolina county guides