On a private well? Radon has a second door
In some homes, well water releases radon into the air every time a tap runs. A separate problem with separate treatment.
The well-water pathway, plainly
Most radon in most houses comes up through the foundation as soil gas. But homes on private wells have a second possible source: the water itself.
Groundwater moving through uranium-bearing rock dissolves radon the way soda holds fizz. Pipe that water into a house and every hot shower, laundry cycle, and running tap shakes some of the gas loose into the indoor air. The bathroom with the longest showers becomes a little radon release valve.
This is a real consideration around Harrisburg because so much of the surrounding area drinks from wells. Inside the city and the boroughs, municipal water makes water-borne radon mostly a non-issue. But north into Perry County and upper Dauphin, west past Carlisle, south toward Dillsburg, rural homes on private wells are the norm, sitting on the same radon-productive geology that gives this region its reputation.
Testing sorts it out. An air test comes first, because air is almost always the bigger source. When air numbers stay stubborn after mitigation, or a home’s well draws from suspect rock, a water sample tells you whether the well is contributing. Our radon testing guide covers how the air side runs.
What treatment involves — and when this page isn’t your problem
Water treatment intercepts radon before the water reaches your fixtures. The heavier-duty industry approach is aeration: equipment near the well line agitates the water, strips the dissolved gas, and vents it outdoors, typically removing most of the radon. For lower water concentrations, granular activated carbon can absorb radon as water passes through a tank. Which fits, and whether either is worth it, depends on the measured water number and the home’s plumbing.
Now the honest scoping. Most homes with a radon problem do not need water treatment. The soil-gas pathway under the foundation is the dominant source in nearly every elevated house, and a standard mitigation system handles it. Water treatment earns its place in a smaller set of cases: well homes with high water readings, and homes where air levels stay elevated after a good soil-gas system is verified.
So the sequence runs test air, fix air, verify, and let the water question come up when the evidence points there. Some well homes end up needing both systems. Most need one. The measurements, not the sales pitch, should decide which home you’re in.
On a well and wondering? Testing settles it.
Frequently Asked Questions
How does radon get into well water?
Groundwater picks it up from the same uranium-bearing rock that puts radon in soil gas. A private well pulls that water straight into the house, and the radon comes out of solution when water gets sprayed or heated: showers, laundry, dishwashers. Municipal water rarely has this problem because storage and treatment give the radon time to escape before it reaches homes.
Is water or soil gas the bigger source?
Soil gas, almost always. EPA guidance uses a rough 10,000-to-1 ratio: about 10,000 picocuries per liter of radon in water adds roughly 1 picocurie per liter to indoor air. That's why the standard advice is to test air first, and look at the well when air numbers stay elevated or the water tests high.
How is water treatment different from an air system?
An air system pulls soil gas from under the foundation. Water treatment intercepts radon at the well line before the water reaches your taps, typically aeration equipment that strips the gas out, or carbon filtration in lighter cases. They solve different pathways, and some well homes end up needing both.