The short answer
North Carolina requires every new private drinking-water well to be tested within 30 days of its certificate of completion for coliform bacteria, 17 inorganic contaminants and pH. To read it, compare each result to its limit in the same units, and note whether the limit is a health standard or a taste-and-staining guideline. Hardness, radon, uranium and PFAS aren't on the required list.
What the state-required test covers
Under North Carolina rule 15A NCAC 18A .3800, in effect since July 1, 2008, the local health department must have water from a newly constructed private drinking-water well sampled and tested by a certified laboratory within 30 days after it issues the well's certificate of completion.[source] The sample is taken at the well or the closest tap ahead of any treatment equipment, so it shows the raw well water.[source]
- Bacteria: total coliform, and if present, fecal coliform or E. coli.[source]
- Metals and other inorganics: arsenic, barium, cadmium, chromium, copper, fluoride, lead, iron, magnesium, manganese, mercury, nitrate, nitrite, selenium, silver, sodium and zinc.[source]
- pH.[source]
The rule also requires the lab's report to include a guide for interpreting the results, and if anything exceeds a public drinking water limit, the state's environmental epidemiology branch sends information and recommendations through your local health department.[source] So keep the whole packet, not just the results page.
What the required test doesn't include
The required list is a solid baseline, but it isn't everything. Comparing it against common Piedmont well issues, these are not on it:[source]
- Hardness. Matters for scale and for sizing a softener. See our Charlotte hardness explainer for how to read it.
- Radon and uranium. Naturally occurring in many Piedmont rocks. See our radon in NC well water guide.
- Volatile organic compounds and pesticides. NC DHHS recommends testing for these every five years, and yearly for a pesticide known to be used near you.[source]
- PFAS. Requires a specific lab method if you're concerned.
How to read each line
- Step 1
Match the units
Results may be in mg/L (same as ppm) or µg/L (same as ppb). 1 mg/L equals 1,000 µg/L. Arsenic's limit, for example, is 0.010 mg/L, which is the same as 10 µg/L.[source] Most misreadings come from comparing numbers in different units.
- Step 2
Check "ND" and "<"
"ND" or a "less than" sign means the lab didn't detect it above its reporting limit. That's a good result, not a missing one.
- Step 3
Identify the kind of limit
A maximum contaminant level (MCL) is an enforceable health-based limit for public water systems. A secondary standard is a non-enforceable guideline for taste, color and staining.[source] Lead and copper use "action levels" instead.[source]
- Step 4
Compare and flag
Anything above a health limit is a priority. Anything above a secondary guideline is a nuisance worth fixing if it bothers you.
| Contaminant | Limit | Type |
|---|---|---|
| Arsenic | 0.010 mg/L (10 µg/L)[source] | MCL (health) |
| Nitrate (as nitrogen) | 10 mg/L[source] | MCL (health) |
| Nitrite (as nitrogen) | 1 mg/L[source] | MCL (health) |
| Lead | 0.015 mg/L; 0.010 mg/L from Nov. 1, 2027[source] | Action level |
| Copper | 1.3 mg/L[source] | Action level |
| Fluoride | 4.0 mg/L (MCL); 2.0 mg/L (secondary)[source][source] | Health and aesthetic |
| Iron | 0.3 mg/L[source] | Secondary (staining, taste) |
| Manganese | 0.05 mg/L[source] | Secondary (staining, taste) |
| pH | 6.5–8.5[source] | Secondary (corrosion, taste) |
What to do with the results
Sort the results into three groups: health limits exceeded, nuisance guidelines exceeded, and everything fine. Health items come first, and each has its own treatment category. For example, arsenic is common in Union County's slate belt, which our Union County arsenic guide explains, and iron and manganese cause the orange and black staining covered in our stains guide.
If you'd like a second set of eyes, our new-well test results page covers how we can go through a report with you, and our water testing service can add the tests the state panel leaves out. Building a home? Our guide to well water in new construction in Union County covers timing.
Remember that this first test is a snapshot. NC DHHS recommends retesting bacteria every year and metals, nitrate, nitrite, lead and copper every two years.[source] Our well testing schedule guide covers when to retest sooner.