Mitigation
Radon in well water: what treatment costs
Short answer
Removing radon from a private well costs more than a radon system for air: Massachusetts puts systems for radon in well water at $3,000 to $5,000, and the University of Georgia's radon program puts an aeration system at about $4,000 installed and a granular activated carbon (GAC) filter at about $1,000 installed. Which one fits depends on how much radon is in the water, so test the water, and the air, first.
Published figures
What radon water treatment costs
Two public bodies publish a figure for treating radon in well water: Massachusetts's health department and the University of Georgia's radon program. Their figures are below, each in the dollars of its year; none is adjusted or averaged.
about $1,000
Georgia
Granular activated carbon (GAC) filter for well water, installed
Published 2025
$3,000 to $5,000
Massachusetts
A system for radon in well water
about $4,000
Georgia
Aeration system for well water, installed
Published 2025
A whole-house system costs more than a radon system for air, which public agencies put at $500 to $3,500 (see every published mitigation cost). A water system is fitted where the water enters the house, so it treats the water for the whole home before it reaches the pipes.
Choosing a system
Aeration or carbon filter: the two treatments
Whole-house treatment at the point of entry usually means either a granular activated carbon (GAC) filter or an aeration system, and it can remove radon from the water before it reaches the home's pipes. Aeration bubbles air through the water, or draws the water into a holding tank, and vents the radon gas outside. A GAC filter traps radon on activated carbon until the radon decays.
Aeration
Bubbles air through the water and vents the radon outside. Up to 99% effective; generally the choice above 10,000 pCi/L.
- Georgiaabout $4,000
Usually costs more than a carbon filter, and needs yearly cleaning.
Granular activated carbon (GAC)
A carbon filter holds the radon back. Over 95% effective below 10,000 pCi/L, and much less above it.
- Georgiaabout $1,000
Usually costs less, but the filter can collect radioactivity and may need special disposal.
Either kind of system
Massachusetts gives one range for whole-house systems for radon in well water, without naming the treatment.
- Massachusetts$3,000 to $5,000
Ask each quote which treatment it is for, so the totals compare like with like.
Aeration typically removes 95 to 99 percent of the radon and needs yearly cleaning and a vent to the outdoors. GAC typically removes 85 to 95 percent and usually costs less, but the filter can collect radioactivity, so it may need a radiation shield around the tank and a special method of disposal. Both have advantages and drawbacks worth discussing with your state radon office or a water treatment professional.
Reading a water result
Which level calls for which treatment
There is no federal or state action level for radon in drinking water at present. The University of Georgia's radon laboratory publishes its own reading of radon-in-water results, tying each band to a treatment:
| Radon in water | What the laboratory says | Treatment it suggests |
|---|---|---|
| Below 300 pCi/L | Low: no considerable health risk from swallowing it | No treatment needed |
| 301 to 4,000 pCi/L | Slightly raised, and may not be a significant health risk | GAC, if you are concerned |
| 4,000 to 10,000 pCi/L | A significant health risk if swallowed, and may raise indoor air radon | Whole-house GAC or aeration |
| Above 10,000 pCi/L | A significant health risk if swallowed, and may raise indoor air radon | Whole-house aeration |
Below 300 pCi/L
- What the laboratory says
- Low: no considerable health risk from swallowing it
- Treatment it suggests
- No treatment needed
301 to 4,000 pCi/L
- What the laboratory says
- Slightly raised, and may not be a significant health risk
- Treatment it suggests
- GAC, if you are concerned
4,000 to 10,000 pCi/L
- What the laboratory says
- A significant health risk if swallowed, and may raise indoor air radon
- Treatment it suggests
- Whole-house GAC or aeration
Above 10,000 pCi/L
- What the laboratory says
- A significant health risk if swallowed, and may raise indoor air radon
- Treatment it suggests
- Whole-house aeration
Testing first
Test the water, and the air, before you buy
$25
Vermont's health department's radon in water test kit from its laboratory (2026).
Testing a water supply takes different devices and procedures from testing the air, so you need a water kit from a laboratory. Although radon gets into some homes through water, test the air first: radon coming in from the soil is usually a much larger risk than radon from water. If you have a private well, test both.
Running costs
Ongoing costs and what to check before buying
Weigh both the price and the cost of running a system: electricity, supplies and filters, repairs and general upkeep, along with how much radon it removes, how long it lasts and its warranty. Home water treatment systems are not regulated by federal or state law, so look for a system certified by NSF International or the Water Quality Association.
FAQ
Radon in water cost questions
How much does it cost to mitigate radon in well water?
Massachusetts puts systems for radon in well water at $3,000 to $5,000. The University of Georgia's program puts aeration at about $4,000 installed and a GAC filter at about $1,000 installed.
Is a carbon filter or aeration cheaper?
A GAC filter usually costs less than aeration. Aeration removes more radon (typically 95 to 99 percent, against 85 to 95 percent), and the University of Georgia's laboratory suggests it above 10,000 pCi/L.
Does a radon water filter need maintenance?
Yes. Aeration needs cleaning every year, and a GAC filter can collect radioactivity, so it may need a radiation shield around the tank and care in disposal.
How much does a radon water test cost?
Vermont's health department sells a radon in water test kit for $25 from its laboratory. Ask your state radon program about its own.
Should I fix radon in the air or the water first?
Test the air first: radon coming in from the soil is usually a much larger risk than radon from water. With a private well, test both.