The short answer
North Carolina requires every newly built private well to be tested by the state lab or a state-certified lab before it's used as a drinking water source, within 30 days of the well's completion. That test covers bacteria, pH, nitrate and metals including arsenic, lead, iron and manganese. In Union County, arsenic shows up above the federal standard in roughly one in five tested wells, so read that line closely, and add hardness and radon if you want them answered.
What North Carolina requires for a new well
All newly constructed private wells in North Carolina must be tested by the State Laboratory of Public Health (scheduled through your local health department) or a state-certified commercial lab before the well is established as a drinking water source, and the bacterial and chemical tests should happen within 30 days of the well's completion.[source]
The law that created the requirement lists what the health department tests for: arsenic, barium, cadmium, chromium, copper, fluoride, lead, iron, magnesium, manganese, mercury, nitrates, nitrites, selenium, silver, sodium, zinc, pH and bacterial indicators.[source] That's a solid baseline. It's a one-time test, though; after that, testing is up to you as the owner.[source]
What Union County well data shows
Several studies have looked at Union County private wells. Their numbers describe wells that were tested, which skews toward people who had a reason to test, so they're not a prediction for any one well. They do show which lines on your report deserve the closest look:
19.46%
Tested wells above the 10 µg/L arsenic standard
1,003 of 5,154 wells tested through the state lab, 1998–2019.
26.5%
Well samples above the NC 0.05 mg/L manganese standard
Of 2,986 samples, 2000–2011.
19.0%
Well samples above the NC 0.3 mg/L iron standard
Of 2,986 samples, 2000–2011.
5.8%
Well samples with pH outside 6.5–8.5
Of 2,985 samples, 2000–2011.
Arsenic is the headline. A separate state assessment found 21.0% of 2,993 private well samples above the same 10 µg/L standard between 2000 and 2011.[source] Arsenic has no taste, color or smell, so the lab result is the only way to know. Our arsenic in Union County wells article goes deeper, and well water arsenic treatment covers the options.
Lead is a different story. In a 2023 UNC study of 224 Union County wells, 9% of samples were above 15 ppb, and the researchers associated lead with household plumbing fixtures rather than the groundwater.[source] In new construction, that points at fixtures and fittings, which is another reason the first test after move-in is worth doing.
What the state test doesn't cover
- Hardness. It's not on the list. Three USGS monitoring wells in Union County ranged from 30 to 151 mg/L, soft to hard, so it varies well to well.[source] Add it if you're deciding about a softener.
- Radon in water. Also not on the list. A USGS study of Piedmont and Blue Ridge crystalline-rock aquifers found radioactive constituents, mainly radon and gross-alpha activity, at high levels in about 30 percent of the study area.[source] See radon and uranium in well water.
- Uranium. Not on the list either; ask the lab if you want it.
- Pesticides and volatile organic compounds. NC DHHS suggests testing for these every five years, and yearly if you know a specific pesticide is used nearby.[source]
Timing it around closing and move-in
- Step 1
Ask for the paperwork early
Ask your builder or seller for the well's completion paperwork and the state test results. If the results aren't back yet, ask when the sample was or will be taken.
- Step 2
Read the report line by line
Look at arsenic, manganese, iron, lead, pH and bacteria first. Our guide to reading your NC new-well test explains each line, and our new well test results page covers next steps.
- Step 3
Fill the gaps
If you want hardness, radon or uranium answered, order a certified-lab test that adds them. Doing it before move-in lets you plan treatment instead of reacting to it.
- Step 4
Design treatment from the numbers
Match equipment to what the test found: for example, an RO system certified to NSF/ANSI 58 to reduce arsenic at the kitchen tap, or iron and manganese filtration at the point of entry.
- Step 5
Retest after treatment
Confirm the treated water matches what the system should deliver, then keep up the routine schedule: bacteria every year and metals, nitrate and nitrite every two years.[source]
Treatment and installation
Well treatment equipment connects to your plumbing, so an independent licensed plumber does that work under their own agreement with you. Our Union County water page has more local context, and how it works lays out the full test, design, install and retest sequence.