North Carolina
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North Carolina water profile

Nitrate in North Carolina community water systems

North Carolina's higher nitrate does not read like farm country: it gathers in the fast-growing Piedmont counties, where thousands of small community systems and subdivisions draw from fractured rock threaded with septic systems. See where the pattern concentrates and what each reporting system measured in the three years from August 9, 2023 to August 9, 2026.

Browse all 1,971 North Carolina systems →

Search by the utility or system name shown on a water bill. Example: City of Raleigh Public Utilities. Private wells are not in this inventory.

99%
of the state’s 1,982 active community water systems have a current result here
1,971
systems with a current nitrate result
9,505,866
people served by those reporting systems
2.9%
of reporting systems at or above 5 mg/L
How to read these numbers Each system is placed into a band by its most recent reported result within a rolling three-year window. The bands describe how strongly human activity, read from nitrate, has marked a water source; they are not a safety verdict. Figures describe system reporting, not nitrate measured at an individual tap.

How North Carolina's systems fall across the five bands

Most systems report below 3 mg/L

Natural background
0.00–0.99 mg/L as N
1,354 systems · 8,720,643 served
Human impact likely
1.00–2.99 mg/L as N
394 systems · 605,194 served
Human impact clear
3.00–4.99 mg/L as N
165 systems · 111,530 served
Health-study range
5.00–9.99 mg/L as N
58 systems · 68,499 served
Above the federal limit
10.00 mg/L and above
0 systems · 0 served

Each system appears in one band only, placed by its most recent reported result in the current three-year window. Counts sit beside people served so a small number of larger systems cannot hide behind a row of tiny ones. Of the 58 systems reporting 5 mg/L or more, 12 stayed at or above 5 across the whole three-year range; the other 46 reached it only on a high sample and otherwise ran lower.

Most recent reading Jul 2026; the typical system was last tested around Feb 2026. 1,655 systems sampled their own water; 316 systems carry a supplier’s result.

The named systems

Every reading here belongs to a utility with a name

Highest recent readings
SystemMost recent resultBandBased onPeople served
Monterrey S/D8.80 mg/LMay 2026Health-study range12 samples69
Sunny Acres I8.54 mg/LMay 2026Health-study range12 samples50
Baywood Forest S/D8.46 mg/LMay 2026a high point — runs lowerHealth-study range24 samples533
Chapel Grove Mhp8.45 mg/LMay 2026a high point — runs lowerHealth-study range12 samples110
Hickory Village Mhp8.34 mg/LMay 2026a high point — runs lowerHealth-study range15 samples165
Hickory Grove Mhp7.86 mg/LMay 2026a high point — runs lowerHealth-study range12 samples69
Buffaloe Road Mhp7.60 mg/LFeb 2026a high point — runs lowerHealth-study range22 samples162
Twin Oaks Tp7.44 mg/LApr 2026Health-study range11 samples77
Largest systems
SystemMost recent resultBandBased onPeople served
Charlotte Water0.50 mg/LFeb 2026Natural background15 samples1,163,701
Raleigh, City Of0.50 mg/LJan 2026Natural background6 samples640,000
Winston-Salem, City Of0.50 mg/LJun 2026Natural background105 samples388,060
Durham, City Of0.50 mg/LFeb 2026Natural background8 samples322,083
Greensboro, City Of0.50 mg/LMay 2026Natural background6 samples319,588

Each result shows its date and what it rests on, so a lone sample is never taken for a settled measurement. A single high sample is not a complete account of what a household drinks.

Where higher nitrate concentrates

Higher results gather in the growing Piedmont

Human impact is clear on drinking water served in 34 of North Carolina’s 100 counties. Each is shaded by how many of its systems reported 3.00 mg/L as N or above. Shading counts systems, not severity — a county with many small utilities can outrank one holding a single larger system that reads higher. The table beside the map splits the two bands so that difference stays visible.

NC counties shaded by number of community water systems reporting nitrate at or above 3.00 mg/L as NCounties are shaded by how many community water systems reported nitrate at or above 3.00 mg/L as N in the three years from August 9, 2023 to August 9, 2026. The same counts appear in the table below this map.Rockingham County — 2 systems at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveFranklin County — 3 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveRandolph County — 5 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveYadkin County — 1 system at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveAlexander County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveOrange County — 2 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveCabarrus County — 2 systems at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveIredell County — 13 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveGuilford County — 10 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveEdgecombe County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveForsyth County — 2 systems at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveLincoln County — 4 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveDurham County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveJohnston County — 0 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveChatham County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveCumberland County — 2 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or aboveMoore County — 3 systems at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveSurry County — 3 systems at 3.00–4.99 mg/L as N; 2 systems at 5.00 mg/L as N or aboveHoke County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveWatauga County — 2 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveBuncombe County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveBurke County — 5 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveMcDowell County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveCaswell County — 2 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveHenderson County — 5 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveGaston County — 32 systems at 3.00–4.99 mg/L as N; 15 systems at 5.00 mg/L as N or aboveDavie County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveCatawba County — 10 systems at 3.00–4.99 mg/L as N; 5 systems at 5.00 mg/L as N or aboveMecklenburg County — 5 systems at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveNash County — 1 system at 3.00–4.99 mg/L as N; 1 system at 5.00 mg/L as N or aboveStanly County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveWake County — 36 systems at 3.00–4.99 mg/L as N; 16 systems at 5.00 mg/L as N or aboveLee County — 1 system at 3.00–4.99 mg/L as N; 0 systems at 5.00 mg/L as N or aboveRowan County — 5 systems at 3.00–4.99 mg/L as N; 3 systems at 5.00 mg/L as N or above
none1–23–56–1112–2526+Number of drinking water systems reporting ≥3.00 mg/L NO₃–N per county as of August 9, 2026

Wake leads this layer with 16 reporting systems, followed by Gaston, Catawba, Cumberland. Higher results gather in the growing Piedmont.

Counties with the most systems at or above 3 mg/L as N
County3–4.99≥5Total ≥3
Wake361652
Gaston321547
Iredell13316
Catawba10515
Guilford10010

Counts use each system's most recent reported result in the current three-year window. A system appears in only one of the two bands.

Find a specific North Carolina system

What the statewide pattern says

Fractured rock, sprawl, and septic

North Carolina's signal is suburban rather than agricultural: Piedmont fractured-rock aquifers under dense development and on-site wastewater, with small community systems carrying the readings.

Wake County is the best-measured case. Reviewing 5,899 public-system samples, the county’s comprehensive groundwater investigation found nitrate at or above 3 mg/L — the level its analysts treat as indicating human impact — in 19.5 percent of samples, and identified septic-tank effluent as the impact source in affected areas, with fertilizer and land-applied wastewater solids as contributors (Wake County Comprehensive Groundwater Investigation).

The plumbing explains the pattern. The Piedmont’s fractured crystalline bedrock stores and moves water in cracks, so a contaminant can be confined to shallow fractures at one lot and, a few hundred feet away, ride connected fractures hundreds of feet down. USGS’s geochemistry work across the North Carolina Piedmont and Mountains documents exactly that behavior, with oxic shallow water carrying nitrate until depth and reducing conditions allow denitrification (USGS Scientific Investigations Report 2009-5149).

That is why the highlighted counties — Wake, Gaston, Iredell, Catawba, Guilford — are growth counties rather than row-crop counties: the readings come from subdivisions, mobile-home parks and small community wells sitting on fractured rock amid dense septic. Gaston’s strong showing has no county-specific published study this page can cite; the Piedmont-wide mechanism is what the literature supports.

The supported source reading is mixed suburban nitrogen — on-site wastewater first, lawn and legacy agricultural fertilizer behind it — on fractured-rock aquifers — not a certified source at any individual system. The setting fits the national vulnerability picture of nitrogen input on fast-pathway ground (Nolan and Hitt, 2006).

The general science — how nitrate moves, why some ground is vulnerable, and why the legacy lingers — is laid out with its sources on Where nitrate comes from.

Questions this page answers

What the North Carolina pattern does—and does not—say

Where does nitrate concentrate in North Carolina community water systems?

Wake leads this layer with 16 reporting systems, followed by Gaston, Catawba, Cumberland. Higher results gather in the growing Piedmont.

Why is North Carolina's pattern suburban rather than agricultural?

The higher readings concentrate in fast-growing Piedmont counties on fractured-rock aquifers. Wake County's groundwater investigation attributed its affected areas to septic-tank effluent, and the state's geochemistry work shows nitrate moving through shallow fractures under oxic conditions — a sprawl-and-septic mechanism, not a row-crop one.

Does depth protect a Piedmont well?

Sometimes, but not reliably. Fractured rock can connect surface water to hundreds of feet down at one location while a neighboring lot stays shallow-fed. Reducing conditions at depth do promote denitrification, which is why deep wells often run lower — but fracture connectivity makes it a local question only a test answers.

Does a high public-system result mean a nearby private well is high?

No. It is a local sentinel, not a well-specific result. It shows that nitrogen and a transport pathway have reached groundwater in the area; a certified-lab test is still the only way to know a specific private well.

Sources and provenance

What this page rests on

  1. NitrateSmart inventory: 1,971 North Carolina community water systems with a current nitrate result in the three years from August 9, 2023 to August 9, 2026. Figures count people served by reporting systems, not measured tap exposure.
  2. Nolan BT, Hitt KJ (2006). Vulnerability of Shallow Groundwater and Drinking-Water Wells to Nitrate in the United States. Environmental Science & Technology 40(24):7834–7840.
  3. Dubrovsky NM, and others (2010). Nutrients in the Nation's Streams and Groundwater, 1992–2004. USGS Circular 1350.
  4. Wake County Government. Comprehensive Groundwater Investigation, Final Report — 19.5% of 5,899 community-system samples at or above 3 mg/L; septic effluent identified as the impact source in affected areas.
  5. USGS (2009). Groundwater geochemistry of the Piedmont and Mountains provinces of North Carolina. Scientific Investigations Report 2009-5149 — fracture-controlled nitrate transport; denitrification with depth under reducing conditions.