Are you concerned about radon in your drinking water? If so, you may be wondering if an activated carbon filter can remove it.
Carbon filters can remove radon from drinking water. Activated carbon filters can remove 99% of radon in water, which would provide safe drinking water for your family. However, due to carbon’s low affinity for radon, you would need a larger carbon filter with longer contact times than a typical system would provide. Aeration is a better treatment method and is recommended over carbon filtration by the US EPA.
Activated carbon filters are relatively effective at removing radon from drinking water, but there are better treatment options available. If you have radon in your water, or just want to learn more about carbon filters and how well they treat this contaminant, continue reading.
About Radon
Radon is a naturally occurring radioactive gas that can be found in many types of soil and rock. It is colorless, odorless, and tasteless which makes it impossible to detect without testing.
An estimated 50 million people have radon in their drinking water, exposing them to dangerous radiation.
What is radon
Radon is a radionuclide that is produced when uranium, radium, and thorium decay. All radionuclides are considered carcinogens. Radon has a short half-life and is a gas at room temperature.
Radon is soluble in water, so it can enter your home through your drinking water. Since radon is a gas, it can be volatized and inhaled while showering or washing dishes.
How does radon get in my drinking water
Radon is found in areas where crystalline igneous or metamorphic rocks are present. The U.S Environmental Protection Agency (EPA) reports that there are higher levels of radon in ground water throughout New England, the Appalachian uplands region across middle Atlantic states including Maryland and Pennsylvania as well as parts southeastern Kentucky and Tennessee. These areas have the geologic formations that produce radon.
Health concerns with radon
The EPA has classified all ionizing radiation as carcinogenic. Radon is the second leading cause of lung cancer in America, according to a 1999 report by National Academy of Sciences. The primary public health risk from radon is breathing it in the indoor air of homes.
The EPA estimates radon in drinking water causes about 168 deaths per year, 89% of which are due to lung cancers caused by breathing this released form of radiation. The other 11% of deaths are due to stomach cancer caused by drinking radon-contaminated water.
Drinking water standard for radon
Currently, there is no federal standard for radon in drinking water. The EPA proposed Maximum Contaminant Levels (MCL) for radon levels in water back in October 1999. The MCL for a contaminant is the highest level of contamination that may be permitted in drinking water based on cost-benefit analysis. MCLs are enforceable.
The proposed MCL for radon in water is 4,000 pCi/L. EPA’s radon MCL is still in draft form and has not been formally approved.
Although the likelihood of developing cancer decreases with lower doses of radiation, it does not completely vanish.
Activated Carbon
Activated carbon adsorption is an effective and reliable water treatment process. It is considered a best available control technology by the USEPA and is a benchmark for other water treatment methods.
Carbon filters are widely used in residential and commercial water treatment systems to remove a variety of contaminants including taste and odor, chlorination byproducts, VOCs, and THMs.
Read my comprehensive Carbon Design Guide for a detailed explanation of this treatment technology.
How carbon adsorption works
Adsorption is a physical process where contaminants are removed from water by binding to the surface of the carbon media.
Adsorption is different than absorption. Adsorption, which is how carbon filters work, is a physical attraction that attracts a contaminant to the surface of the carbon. Absorption is a bulk process where the substance is taken into (absorbed) the media like a sponge.
Adsorption onto activated carbon works because most organic molecules have a natural affinity for carbon. This means they will stick to the surface of the carbon. To increase the surface area available for adsorption, thousands of tiny pores are created by “activating” the carbon.
Carbon filter components
Carbon filters for residential applications are very simple. They include either a vessel filled with activated carbon (for whole-house systems) or a cartridge that contains carbon (point-of-use filters).
Granular activated carbon, also known as GAC, is the most commonly used type of carbon. GAC looks like the gravel in an aquarium.
Some carbon filters include a particle pre-filter to remove sediment and suspended particles. This protects the carbon from fouling and extends the life of the media.
Many carbon filters, especially whole-house systems, include a bypass valve to allow the flow of water when the vessel is being serviced. Pressure gauges are often installed on the inlet and discharge side of the filter to allow you to monitor the amount of fouling that has occ
Types of granular activated carbon
Carbon is formed by converting organic materials like wood and coal into charcoal. The charcoal is then activating by exposing it to high temperature steam.
1 – Coal-based carbon
Most of the activated carbon used in water treatment is made from coal. The two main types use in carbon are bituminous coals and lignite coal. Coal-based carbon is very hard with pore sizes that make it ideal for removing many of the contaminants found in drinking water.
2 – Coconut shell carbon
Coconut shall carbon is highly prized for its ability to purify air and to remove difficult contaminants like PFAS and lead. This carbon is made from coconut husks. Coconut shell carbon is more expensive than coal-based carbon, but it lasts longer and is more effective at removing certain types of contaminants.
3 – Catalytic carbon
Catalytic carbon is activated carbon that has been modified through the addition of iron-hydroxide or through an enhanced activation process. It has several advantages over conventional carbon including a higher affinity for chlorine and chloramines.
How Well Does Carbon Filtration Remove Radon
Carbon filters can remove 90 to 99% of radon from drinking water. The effectiveness depends on several factors such as the type of carbon, the contact time, and the amount of carbon in the filter.
Contact time and radon treatment
The contact time is the most important parameter for treating radon-contaminated water. Long contact times are required to remove 99% of radon.
Contact time is a measure of the time during which water is in contact with the carbon. Many water treatment engineers use Empty Bed Contact Time (EBCT) to design a carbon treatment system. EBCT is equal to the volume of the empty filter housing divided by the flow rate.
Problems with small carbon filters
In order to achieve effective radon removal (99%), you need a minimum contact time of 10 minutes. Ideally, you will have 15 to 20 minutes of contact time.
A small point-of-use carbon filter won’t give you this much contact time. This is especially true if you run the water at full flow (most of us do this) or use a lot of water. or more minutes are generally required for radon treatment.
Factors to Consider with Carbon Filters
If you are considering a carbon filter for your home, there are some factors you should keep in mind before making a decision.
Installation cost
A carbon filter can be installed as a point-of-use (POU) unit or as a whole-house system. Whole-house systems are also known as point-of-entry (POE) systems. POU systems are less expensive to install, but they only treat water at the sink where they are installed.
Whole-house systems are more expensive to install, but they will treat all of the water in your home. Typical installation costs for POE carbon filtration are between $1,300 to $5,000. The biggest cost is the labor to install the filter. If you’re handy, you can install the system yourself.
An under-sink carbon filter can be installed for less than $100. However, a filter this small would not remove all of the radon from your water.
Maintenance
Carbon filters require maintenance to keep them operating properly. The primary maintenance is replacement of spent carbon – spent carbon is media that has no remaining adsorption capacity.
Small, under-sink filters need to be replaced every few months. Large whole-house filters can last for 6 months to as long as 2 years before they need to be replaced. Often, the carbon will become fouled with sediment or biological growth which would require replacing it more frequently.
For a whole-house carbon unit, you have to remove the carbon from the filter vessel. This is difficult to do and, most people hire a specialty company to do this.
How often do I need to change the carbon
You need to replace the carbon when it becomes spent. This is the point where the media can no longer remove the contaminant from your water.
For a typical residential system, a carbon filter has a service life of 6 months to 1 year. If your carbon becomes fouled with solids or biological growth, you may have to replace it sooner than this.
How much do replacement filters cost
POU carbon filters have a carbon cartridge that is replaced when the media is spent. The cost of an under-sink carbon cartridge is $30 to $350, depending on the size of the unit.
Whole house carbon filters require removing the spent carbon and adding fresh media to the vessel. The cost for this service is $1.40 top $4.50 per pound. A typical whole-house carbon system contains between 100 and 400 pounds of carbon – the cost for this service varies from $140 to more than $2,000.
Whole-house versus under-sink
You have two options when it comes to carbon filtration – whole-house and under-sink.
Whole-house systems treat all of the water entering your home. They are more expensive to install, but they provide clean, safe water to every faucet and shower in your house.
Under-sink systems are less expensive to install, but they only treat the water at the sink where they are installed.
NSF certification
If you are planning to install a carbon filter for your home, you should look for NSF certification.
The NSF certification mark means that the water filter has been tested for safety and to verify the manufacturer’s claims.
Here are the NSF certifications that apply to caron filters:
- NSF/ANSI 42: Certified to reduce aesthetic impurities such as chlorine and taste/odor.
- NSF/ANSI 53: Certified to reduce a contaminant with a health effect. Health effects are set in this standard as regulated by the U.S. Environmental Protection Agency (EPA) and Health Canada.
- NSF/ANSI 401: Certified for emerging contaminants.
Other Treatment Methods that Remove Radon
Aeration is a very effective method for removing radon from drinking water. Aeration is often referred to as air stripping.
This treatment method involves passing the water through a chamber where air is bubbled or blown through it. The radon gas escapes from the water and is vented to the atmosphere.
Aeration can remove 99+% of radon from water. It is effective for both low and high concentrations of radon. Aeration is recommended by the EPA for treating residential drinking water.
Aeration can be used alone, but it is typically used as a pretreatment for other methods, such as activated carbon filtration.
Testing Your Water for Radon
Radon is colorless, odorless, and tasteless. The only way to know if it’s in your water is to test it.
The EPA recommends that all homes with private wells test their water for radon. Radon testing kits are available from hardware stores, home centers, and online retailers.
Costs for radon testing
You can also use a certified lab to test your water for radon. The cost of a laboratory test is $80 to $350.
Tap Score’s radon test
Tap Score’s water test kit provides an accurate and convenient way to measure your drinking water’s radon concentration. If you want the peace-of mind that comes with knowing exactly how much radon is present in your water, then you should try this tap score test kit.
The kit includes everything you need to collect a sample – glassware, chain-of-custody, instruction, and a return shipping label. You’ll receive a detailed report that includes the radon concentration of your water along with an explanation of what your results mean.
Learn more about this radon test kit.
NSF Certified Carbon Filters for Radon Removal
The following carbon filters are certified by NSF to remove radon from drinking water.
| Manufacturer | Brand Name and Model | Type of Filter | Service Cycle | Flow Rate |
| Amway | eSpring Model 100185 (100188) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100188HK) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100188IN) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100188J) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100188K) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100188M) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100188RU) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100188SG) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100188T) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100188TH) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185A (100188A) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185B (100188B) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185D (100188D) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185HS (100188HS) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185MX (100188MX) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185NC (100188NC) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185P (100188P) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185PH (100188PH) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185SK (100188SK) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185UA (100188UA) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185W (100188W) | Counter-Top Connected to Sink Faucet | 1,320 gallons | 0.9 gpm |
| Amway | 100186E | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | 100186J | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | 100186K | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | 100186M | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | 100186ME | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | 100186MX | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | 100186R | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | 100186RK | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | 100186T | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | 100186TH | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | CVX5787 | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100189) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100189HK) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100189IN) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100189J) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100189K) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100189RU) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100189SG) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100189T) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185 (100189TH) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185A (100189A) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185B (100189B) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185D (100189D) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185GR (100189GR) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185HS (100189HS) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185MX (100189MX) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185NC (100189NC) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185P (100189P) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185R (100189R) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185SA (100189SA) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185SK (100189SK) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185UA (100189UA) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
| Amway | eSpring Model 100185W (100189W) | Plumbed-In to Separate Tap | 1,320 gallons | 0.9 gpm |
FAQs
Does reverse osmosis remove radon?
Reverse osmosis does not remove radon from drinking water. Gaseous pollutants such as carbon dioxide and radon are not removed by reverse osmosis.
Does boiling water remove radon?
Boiling water will remove radon from water. Radon is a gas, and its solubility is temperature dependent. As the water boils, the solubility of radon decreases, and it off-gases to the atmosphere. However, you should not boil water to remove radon because it will evaporate and expose you and your family to dangerous radiation.
Does a water softener remove radon?
Water softeners do not remove radon gas from drinking water. Water softeners use ion exchange which does not remove radon.
Final Take on Carbon Filters and Radon
So, do carbon filters remove radon from drinking water? The answer is yes, but it’s not the best option. If you’re looking for a way to remove radon from your water, activated carbon filtration is a good place to start. However, aeration is a better treatment method and is recommended over carbon filtration by the US EPA. Thanks for reading!