Nitrate in North Carolina well water
In North Carolina, <1% of 46,033 private wells tested between 1998 and 2019 had nitrate above the EPA limit (10 mg/L), according to the NC State Laboratory of Public Health (NCWELL).
Nitrate reaches wells from fertilizer, septic systems and manure. Above the limit it can cause methemoglobinemia (blue baby syndrome) in infants under six months, and long-term exposure is associated with some cancers. Shallow and dug wells near farmland or dense septic systems are most at risk.
Check your nitrate number
Type the value from your lab report. It is compared to the EPA limit and the EPA limit, the same way the full interpretation does it.
Test your North Carolina well for nitrate
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
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Systems that remove nitrate
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Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For nitrate
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For nitrate
Aquasana SmartFlow reverse osmosis
under-sink or countertop, about $225
Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.
Rather have it installed and sized for your well? Book a free in-home water test with a licensed local company.
Where to get a well tested for nitrate in North Carolina: certified labs, state programs and prices.
By county, from homeowner tests
Share of private wells above the state guidance level (10 mg/L) in tests homeowners sent to the state lab, 1998 to 2019.
| County | Above state level | Wells tested | Highest |
|---|---|---|---|
| Richmond | 323 | 29 mg/L | |
| Sampson | 602 | 36 mg/L | |
| Northampton | 113 | 15 mg/L | |
| Robeson | 61 | 11 mg/L | |
| Edgecombe | 97 | 13.7 mg/L | |
| Hertford | 60 | 11 mg/L | |
| Greene | 30 | 12 mg/L | |
| Wayne | 271 | 44 mg/L | |
| Anson | 37 | 31 mg/L | |
| Harnett | 115 | 14 mg/L | |
| Lenoir | 79 | 15 mg/L | |
| Alleghany | 81 | 13 mg/L | |
| Chatham | 1,761 | 120 mg/L | |
| Johnston | 558 | 16 mg/L | |
| Scotland | 130 | 12 mg/L |
By county, from individual samples
Public monitoring samples against the EPA limit (10 mg/L); counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Wake | 156 | 96% | 14.9 | 577 mg/L | |
| Greene | 661 | 78% | 5.51 | 401 mg/L | |
| Johnston | 179 | 98% | 3 | 70.8 mg/L | |
| Edgecombe | 139 | 60% | 0.33 | 124 mg/L | |
| Sampson | 113 | 84% | 0.2 | 327 mg/L | |
| Halifax | 33 | 100% | 1.4 | 41 mg/L | |
| Duplin | 86 | 67% | 0.07 | 125 mg/L | |
| Columbus | 32 | 100% | 0.18 | 159 mg/L | |
| Lenoir | 88 | 86% | 0.1 | 45 mg/L | |
| Onslow | 97 | 49% | 0 | 664 mg/L | |
| Chowan | 52 | 96% | 0.125 | 56 mg/L | |
| Orange | 165 | 88% | 0.782 | 31.9 mg/L | |
| Rockingham | 99 | 68% | 0.239 | 38.7 mg/L | |
| Wilson | 35 | 89% | 0.1 | 15 mg/L | |
| Lee | 73 | 70% | 0.343 | 72.8 mg/L |
- St. Marys township, Wake County86% of 59
- Smithfield township, Johnston County62% of 91
- Ormonds township, Greene County45% of 569
- Swift Creek township, Wake County42% of 76
- Township 2, Lower Conetoe, Edgecombe County36% of 123
- Contentnea Neck township, Lenoir County31% of 32
- Bingham township, Orange County17% of 66
- Reidsville township, Rockingham County12% of 49
- Olds township, Greene County10% of 82
- Township 7, Pocket, Lee County7% of 57
- Wilmington township, New Hanover County6% of 35
- Nahunta township, Wayne County4% of 105
- Belvoir township, Pitt County3% of 30
- Chapel Hill township, Orange County3% of 30
- Madison township, Guilford County3% of 306
- Fork township, Wayne County3% of 79
- Harnett township, New Hanover County2% of 58
- Cape Fear township, New Hanover County1% of 76
- Saulston township, Wayne County1% of 80
- Davidson township, Iredell County0% of 58
Sources
- NCWELL private well summaries: County summaries of private well tests run by the NC State Laboratory of Public Health, 1998 to 2019, compiled by the UNC Superfund Research Program (NCWELL database). Counts are tests, not distinct wells; since 2008 every new well is tested once, so most tests are unique wells. Shares are against the NC 2L groundwater standard where one exists (manganese 50 ug/L, lead 15, iron 300) and otherwise the EPA limit. Medians are not used because more than half of results sit at the reporting limit for most analytes. Retrieved September 9, 2026.
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. nitrate counts and shares are listed on each county and town page with their sources.
Analysis: Nitrate in private wells, decade by decade, from the same public records.