Should you test your well water for radon? The short answer is absolutely. If your home uses a private well, radon deserves a spot on your water testing checklist. Most homeowners associate radon with basements and foundations, and that’s fair. But radon can also dissolve into groundwater, travel through your well system, and release into your home every time you shower, run the tap, or do dishes.
Testing your well water for radon (and other contaminants) is worth doing, especially in North Carolina, where the underlying geology makes elevated groundwater radon a real possibility in many areas. Here’s what you need to know about how it happens, what the risks look like, and when to act.
How Does Radon Get Into Well Water?
Radon is a naturally occurring radioactive gas produced when uranium in rock and soil breaks down. It’s colorless, odorless, and tasteless, so there’s no way to detect it without testing.
In much of North Carolina, the bedrock includes granite, gneiss, and schist, rock types with naturally higher uranium concentrations.
As groundwater moves through those formations, it picks up dissolved radon and carries it into private wells. Surface water sources like rivers and reservoirs lose most of their radon to the open air before reaching a tap, which is why this is almost exclusively a private well concern.
Once radon-laden water enters your home, it gets to work immediately. Every time you run the shower, dishwasher, or faucet, radon off-gasses into your indoor air. That secondary inhalation exposure is actually the bigger health risk of the two.
What the Health Risks Actually Are
Radon is the second leading cause of lung cancer in the United States. The EPA estimates it causes roughly 21,000 deaths annually, and the majority of that risk comes from breathing it in, not from drinking it.
The primary concern with radon in well water is what it does to your indoor air quality once it off-gasses during household use. Showering is the most significant source of release: hot water agitates more gas, and bathrooms are small, enclosed spaces where concentration builds quickly.
Ingesting water with elevated radon over time does carry some added risk, mainly for stomach cancer, but it’s considerably lower than the inhalation risk. The two exposures compound each other when both a soil pathway and a water pathway are present in the same home.
Is This a Real Concern in NC?
NC DHHS recommends testing all homes in the state for radon, and that guidance extends to private well water. North Carolina’s geology varies significantly by region.
The mountain counties tend to show the highest radon concentrations, but the Piedmont, which includes the Charlotte metro, sits on ancient crystalline rock formations that can also produce elevated groundwater radon. Levels vary considerably from well to well, even between neighboring properties on the same street.
That variability is exactly the point. You can’t predict your well’s radon level based on your neighbor’s results or your county’s general risk profile. Testing is the only way to know.
NC’s radon program recommends testing indoor air first. If your air test comes back at or above 4 pCi/L, a water test is the logical next step to determine whether your well is contributing to that number.
Even if your air test is below the action level, testing your well water provides a useful baseline, particularly when buying a home or after any significant work on your well system.
Radon in Water vs. Radon in Air
These are related but separate issues. Here’s a quick comparison:
| Consideration | Radon in Air | Radon in Well Water |
| Source | Soil and rock under the home | Groundwater through the well |
| Entry point | Foundation cracks, floors, walls | Released during household water use |
| Primary risk | Lung cancer from inhalation | Off-gassed radon adds to indoor air; some ingestion risk |
| Tested by | Short- or long-term air monitor | Water sample sent to certified lab |
| NC action threshold | 4 pCi/L | Treatment recommended at 10,000 pCi/L or above |
A useful rule of thumb: for every 10,000 pCi/L of radon in your water, expect roughly 1 pCi/L added to your indoor air reading. So a water result of 30,000 pCi/L could be contributing approximately 3 pCi/L to your air, stacking on top of whatever radon is entering through the foundation.
NC’s Radon-in-Water Advisory Committee recommends treatment for private wells at or above 10,000 pCi/L, especially when combined with an existing indoor air radon issue. Wells between 4,000 and 10,000 pCi/L fall into an optional treatment zone worth discussing with a professional based on your full picture.
How Does Professional Well Water Testing Work?
Testing for radon in well water requires a water sample handled and analyzed by a certified laboratory. Here’s the process in brief:
- Sample collection: A technician collects a water sample using procedures that prevent radon from off-gassing out of the sample before testing, which would skew results low.
- Lab analysis: The sample is measured in picocuries per liter (pCi/L) by a certified lab.
- Results review: A certified inspector walks you through the findings and outlines the next steps if levels are elevated.
Proper sample handling is what separates reliable results from misleading ones. That’s the main reason professional testing is worth it over DIY kits for this particular contaminant.
What Happens if Levels Are Elevated?
Two main treatment options exist for private wells with elevated radon:
- Aeration systems bubble air through the water supply before it enters the home, causing radon to off-gas, which is then vented outside. They’re highly effective and generally the preferred choice at higher concentrations.
- Granular activated carbon (GAC) filters pass water through carbon material that traps radon before it reaches your taps. They tend to cost less upfront, but the filter accumulates radioactivity over time and requires careful disposal when replaced.
A professional can recommend a better fit based on your water usage and radon concentration. After installation, follow-up testing confirms the system is working. America’s Choice Inspections performs the testing but refers clients to certified mitigation contractors for treatment.
Related Questions to Explore
What else should you test private well water for? Radon is one item on a longer list. Private wells are unregulated, meaning no outside agency is monitoring your water quality. Common contaminants worth testing for include coliform bacteria, E. coli, nitrates, lead, arsenic, and pH. FHA and VA loans typically require water quality testing as a condition of financing on homes with private wells.
Does radon in air testing cover the risk from well water? Not entirely. An air test measures the total radon concentration in your home’s indoor air, but it doesn’t tell you where the radon is coming from. If your air reading is elevated, water testing helps determine whether your well is a contributing source, which matters for deciding on the right mitigation approach.
What does mold testing involve, and when is it recommended? Mold and radon are separate concerns, but both fall under the category of indoor air quality issues that aren’t visible to the eye. Mold testing involves collecting air or surface samples that are analyzed by a lab. It’s worth considering after water damage, when musty odors are present, or when unexplained respiratory symptoms arise in a home.
What is thermal imaging, and how is it used during a home inspection? Thermal imaging uses infrared camera technology to detect temperature differences behind walls, ceilings, and floors. During an inspection, it can reveal moisture intrusion, missing insulation, and electrical hot spots that aren’t visible during a standard walkthrough. It’s often added as a specialty service alongside a general home inspection.
When to Call a Professional
If you’re buying a home with a private well in the Charlotte area or surrounding communities, schedule water quality testing before closing.
Don’t rely on a previous owner’s results or assume the well is fine because the home looks well-maintained.
If you already live in a home with a well and haven’t tested your water recently, or if a recent air radon test came back elevated, adding a water test is a straightforward next step. The combination of both tests gives you the most complete picture of what you’re actually dealing with indoors.
Conclusion
Radon in well water doesn’t get the same attention as radon in air, but for private well owners in North Carolina, it’s a real and testable part of the overall radon picture. The risk is mostly about what happens after radon off-gasses from your water into your indoor air, and the only way to know your actual exposure is to test.
At America’s Choice Inspections, we’ve been serving Charlotte and surrounding communities since 1998, offering well water quality testing, radon testing, and comprehensive home inspections.
If you have a private well and want to know what’s in your water, reach out to schedule your inspection today.