Skip to content
RADON411
Water5 min read

How do you get radon out of water?

By Radon411 Editorial TeamUpdated How we research

Short answer

Radon is removed from water with point-of-entry treatment, which treats all the water before it reaches the taps, usually by aeration, which typically removes 95 to 99 percent, or a granular activated carbon filter, which typically removes 85 to 95 percent. A filter at a single tap does not address radon released into the air.

Next step: find out how well water is tested and treated. Radon in water

Most of the risk from radon in water comes from radon released into the air when water is used for showering and other household purposes. Point-of-entry treatment removes radon before the water enters the home's pipes; a point-of-use device treats only a small share of the water, such as the water you drink.

Aeration is generally more efficient and suits higher levels; it needs annual cleaning and vents the radon outdoors. GAC filters usually cost less and suit moderate levels, around 5,000 or less in water, but they can collect radioactivity and may need a special method of disposal. Discuss the choice with your state radon office or a water treatment professional.

In most cases radon entering through water is a small risk compared with radon from the soil, so test and fix the air too.

What to do next: test the air, then the water, and if the water result is high, get a quote for point-of-entry treatment and retest the water once it is installed.

At a glance · 1 min read

Two places to treat water: the entry or the tap

A home's water can be treated in one of two ways: point-of-entry, where the water comes into the house, or point-of-use, at a single tap. For radon, the difference is decisive, because most of the risk from radon in water comes from radon released into the air when water is used for showering and other household purposes.

Point-of-entry against point-of-use treatment for radon
FeaturePoint-of-entryPoint-of-use
Where it treatsAll the water, before it reaches the home's pipesOne tap, a small share of the water, such as drinking water
Effect on radon in the airRemoves radon before it can be released indoorsNot effective against radon released into the air from all the water used
Usual equipmentAeration or a granular activated carbon filterA device at the tap
Read moreA paragraph, 1 min

So the fix for radon in water is whole-house treatment at the point of entry.

In a picture · 1 min read

Aeration and carbon filters compared

Point-of-entry treatment usually uses one of two methods. Aeration releases the radon from the water and vents it outdoors. A granular activated carbon filter, or GAC filter, holds it in the carbon.

Typical radon reduction, EPA

Radon in private well water

  • Private well water: aeration95 to 99 percentGenerally more efficient than GAC; requires annual cleaning to maintain effectiveness and to prevent contamination; requires venting radon to outdoors.
  • Private well water: granular activated carbon (GAC)85 to 95 percentLess efficient for higher levels than aeration; use for moderate levels, around 5,000 pCi/L or less in water.
Typical radon reduction for aeration and for granular activated carbon.
Read moreA table, 1 min
Aeration and GAC for radon in private well water
FeatureAerationGranular activated carbon (GAC)
Typical reduction95 to 99 percent85 to 95 percent
Best forHigher levels; generally more efficient than GACModerate levels, around 5,000 pCi/L or less in water
CostUsually more than a GAC filterUsually less than aeration
UpkeepAnnual cleaning; radon vented outdoorsRadioactive by-products can build up on the carbon; may need a radiation shield and care in disposal
Show all 4 rows

Overview · 1 min read

Choosing between them

Both methods have advantages and disadvantages that are worth discussing with your state radon office or a water treatment professional. The water test result is the starting point: GAC suits moderate levels, and aeration is the more efficient choice as levels rise.

Read moreA note, 1 min

At a glance · 1 min read

Before you treat: test, and test the air

Treatment follows a test. If you have tested the air and found a radon problem and your water comes from a well, have the water tested; well owners can also test both to see which options fit. In most cases radon entering through water is a small risk compared with radon from the soil, so fix a high air level too.

The order of work for a home on a well
StepWhat to do
1Test the air in the lowest lived-in level
2Test the well water for radon
3Fix the air if it is high
4Treat the water at the point of entry if it is high
5Retest the water after treatment is installed
Show all 5 rows
Read moreA paragraph, 1 min

See how to test for radon in well water.

Overview · 1 min read

Public water supplies

Radon in water is not usually a problem when the source is surface water, and is more likely when the source is groundwater, from a private well or a public system that uses groundwater. Some public systems treat their water to reduce radon before delivering it. If you are on a public supply and concerned about radon, contact your water supplier.

Questions · 1 min read

Questions about removing radon from water

How do you remove radon from well water?

With point-of-entry treatment for the whole home, usually aeration or a granular activated carbon filter.

Does a water filter remove radon?

A granular activated carbon filter at the point of entry typically removes 85 to 95 percent. A filter at a single tap treats only a small share of the water and does not address radon released into the air.

Can I treat only my drinking water?

A point-of-use device treats only a small portion of the water, such as the water you drink, and does not reduce the risk from radon released into the air from all the water used in the home.

Which is better, aeration or carbon?

Aeration is generally more efficient and suits higher levels; carbon usually costs less and suits moderate levels, around 5,000 pCi/L or less in water.

Is radon in water a big risk?

In most cases it is a small risk compared with radon from the soil. Most of it comes from radon released into the air when the water is used.

Do carbon filters become radioactive?

They can collect radioactivity and may need a radiation shield around the tank and a special method of disposal.

Water

Related guides

Radon in well and household water: when it matters, how a water test works, and treatment.

Everything in WaterOther guide topics
  • Overview page

    Radon in water

    How radon gets into water, who it affects most, how a water test differs from an air test, and how elevated water radon is treated.

    Open the page
  • Overview page

    Well water and radon

    Why private wells are the main concern for waterborne radon, and what public water treatment changes about that risk.

    Open the page
  • Overview page

    Water testing for radon

    How a water-specific radon test works, why it is different from an air test, and where to send a sample.

    Open the page