Water problem
Radon in well water
Radon gas dissolved in groundwater. Most of the household risk comes from radon in air rather than water, so the air test comes first and often settles the question.
What you might notice
- None in the water itself
- An elevated indoor air radon result
- A drilled bedrock well in a known radon area
Test the air before you test the water
Radon is a naturally occurring radioactive gas produced by the decay of uranium in bedrock. It enters buildings in two ways: directly from the soil through the foundation, and dissolved in water from a private well.
For almost every property, the soil pathway dominates. Radon entering through the foundation typically accounts for far more of the household exposure than radon released from water during showers and washing.
So the first test is an indoor air radon test. It is inexpensive, widely available, and it answers the question that determines whether anything else is worth doing. Testing the water first is a common way to spend money in the wrong order.
Reading the results together
If indoor air radon is low, treating the water is very unlikely to be worthwhile, even on a private well in a known radon area.
If indoor air radon is elevated and the property is on municipal water, the source is the soil and the answer is a sub-slab mitigation system. Water is not a contributor, because radon dissipates in open reservoirs and distribution systems.
If indoor air radon is elevated and the property is on a private well, test the water as well. Radon released from water during showering, laundry, and dishwashing contributes to the air concentration, and where the well is a significant contributor, mitigation alone will not reach the target.
Treatment options for water, if it comes to that
Aeration systems strip radon out of the water and vent it outside, then the treated water continues into the house. This is generally the preferred approach for higher concentrations because nothing accumulates.
Granular activated carbon units adsorb radon and suit lower concentrations. They need careful siting, because the carbon bed concentrates radioactivity over time and has to be managed accordingly.
Both are point-of-entry systems, because the exposure route is inhalation during water use throughout the house rather than drinking. A filter at the kitchen tap does not address this problem, and that surprises people who expect drinking water treatment to be the answer.
How to confirm it
Test indoor air first, because that is where the dominant exposure pathway is and it is the cheaper test. If air radon is elevated and the property is on a private well, a water test establishes how much the water is contributing when it is agitated by showers and washing.
The test that settles this is indoor air radon test first, then a laboratory water radon test if indicated. We include what we can measure on site in a free water test, and we will tell you plainly when a certified laboratory is the right next step rather than anything we can do at your kitchen tap.
When not to treat it
If indoor air radon is low, treating the water is very unlikely to be worthwhile. Where air radon is high, a sub-slab mitigation system usually addresses far more of the exposure than water treatment would, and for less money.
Treatment options that actually apply
These are the equipment types that address this problem. Each page states what the equipment does not do, so you can rule it out quickly if your situation does not match.
- Well water systems. A treatment train assembled around a current laboratory test, in stages.
What none of these will do
- Anything the test did not look for. A basic panel does not cover arsenic, radon, or PFAS unless requested.
- Changes in the well over time, which is why annual testing matters.
- A failing well casing or a septic system too close to the wellhead. Those are construction problems, not filtration problems.
Getting it installed
Once a test has confirmed the problem and narrowed the equipment, the practical questions are access, space, and whether anyone's permission is needed. Those are covered on the installation pages, along with what a visit involves and how long it takes.
- Free water testing. 45 to 60 minutes.
- All installation services
- What installation costs
Other water problems
Sources
- Radon in Drinking Water. US Environmental Protection Agency, 2024.
Next step