Every Pipe Through Your Slab Is a Hole: Radon and Plumbing in Raleigh Homes
If a plumber has ever worked on your house, there is a good chance he cut a hole in your foundation. That is how pipes get through a concrete slab: someone cuts the opening, sets the pipe and fills the gap. The fill has to hold up against the ground for decades. In Wake County, where radon is a real concern, that ground is worth thinking about.
Why Wake County deserves a test
Raleigh is not the mountains, but the Piedmont has its own radon story. NC Health News has described Warren, Franklin, Vance and Wake counties as a Piedmont band with high levels. In December 2025, NCDHHS reported that 90 of North Carolina’s 100 counties have elevated radon levels, and it recommends that every home be tested. A county average can’t tell you about your house. Only a test can.
Three places plumbing comes into it
The CDC lists the ways radon gets into a home, and three of them involve plumbing.
Gaps around service pipes. Every pipe that passes through your foundation or slab is a spot where a seal can crack or shrink over the years. In a slab-on-grade house, much of the plumbing runs through the floor itself.
The sump hole or opening. A sump pit connects directly to the soil around the house. Ask your plumber whether yours has a sealed lid or just a loose cover.
Private wells and groundwater. The CDC notes that high radon in a water supply is more likely when the source is groundwater.
City water or a well?
That last point decides whether the third path is yours. The CDC says high radon in water is more likely with groundwater, meaning private wells, than with most public supplies, which mainly draw from surface water. On city water, the air in your house is what to test.
On a well in eastern Wake County, pay more attention. CBS17 reported in 2019 that about 6,000 of roughly 20,000 wells in a “vulnerable area” may exceed the guidance level for radon. That is an estimate, not a result for your well. The state’s advice is to test the air first and test the water if the air is elevated. Wake County Environmental Health takes calls at 919-893-WELL.
What to do this week
- Test the air. Kits run $20 or less at hardware stores, according to the state. NCDHHS said it will offer free kits starting January 1, first come, first served. Put the kit in the lowest level you live in, keep windows and exterior doors shut, and follow the directions. The EPA’s action level is 4.0 pCi/L.
- Ask your plumber to show you. A minute of walking the house tells you where pipes pass through the foundation and whether the sump is sealed.
- Retest after plumbing or foundation work. New fixtures, re-piping and a new sump all change how the slab behaves, so an old result may not still be true.
- Don’t count a sealed gap as the fix. Sealing around a pipe is good practice. But it doesn’t pull radon out from under the slab, so a high result still means a radon professional.
Buying a house? Put the radon test on your list for the due diligence period and order it on day one.
If the test comes back high
A high result calls for a radon system, and plumbing companies don’t install those. North Carolina doesn’t license radon testers or mitigators, so there is no state card to ask for. The NC Radon Program points homeowners to national certifications from the NRPP and the NRSB, and that is where I would start.
I keep York PA Radon Pros, so I spend a lot of time on what separates a good contractor from a rushed one, and the answer is the same in any state. Have them walk your house and show you where the pipe will run and where the fan will sit. Get the price, the fan warranty and the guaranteed result in writing, and ask who runs the test once the system is in. Someone who can’t explain the pipe route for your house hasn’t looked at it yet.
The short version
- The state says 90 of 100 North Carolina counties have elevated radon, and Wake is in the Piedmont band.
- Plumbing opens three paths: gaps around pipes, an open sump and private well water.
- On city water, test the air. On an eastern Wake well, test the air first and the water if the air is high.
- Retest after plumbing or foundation work, and call a radon professional for a high result.
A & A Plumber Inc. is a trusted, family-owned plumbing company based in Raleigh, NC. Serving Raleigh, Cary, and the surrounding Triangle area, their licensed technicians specialize in emergency repairs, drain cleaning, tankless water heater installations, and sewer line care. The team shares practical tips and insights to help homeowners protect their plumbing systems, prevent leaks, and lower water bills.