Why is there a relationship between Radon limit in water that depends on air?

[Mswlogo]

I had my water tested by the well company when our well was installed. They reported 2023 for radon and they never flagged it as a concern.

Reading up on it, it varies by state what’s an acceptable level and it’s well below limit. Unless you have radon in the air above 4. And I do (in the cellar). It’s like 20 in the cellar but like 2 on the main floor. But house is not fully sealed and functioning yet so I have to see where things settle out before I address that.

I’m quite familiar with radon removal and installed a system myself in another home.

So is it the fact that the radon in water will contribute to the radon in the air? Is radon harmless if drank?

It turns out a GAC filter can remove the radon from the water. I wonder if the Filox filter I just installed alone will as well.

How toxic will the GAC filter get. How would you know it’s “full”.

I have an AirThings Wave radon monitor (one of the best investments ever). I wonder if there is something similar to monitor water.

 

[Gsmith22]

I’m quite familiar with radon removal and installed a system myself in another home.

So is it the fact that the radon in water will contribute to the radon in the air? Is radon harmless if drank?

It turns out a GAC filter can remove the radon from the water. I wonder if the Filox filter I just installed alone will as well.

How toxic will the GAC filter get. How would you know it’s “full”.

I have an AirThings Wave radon monitor (one of the best investments ever). I wonder if there is something similar to monitor water.

There are 4 radioactive decay chains and they all include Radon (with half lifes generally measured in days). Radon is a gas so it can move up through the ground and into your home with relative ease while the other decay chain products can't (they are solids and would need to be physically excavated). Due to being a gas, radon is detectable in basement air as the radon moves upward through the ground (basement is in its way) and is the common concern. But radon also dissolves itself in ground water that it comes in contact with which when pumped from the ground, will also off gas into the air as soon as it isn't sealed in a plumbing system. So if you have a well with radon infused ground water, it will generally off gas at the plumbing fixture (into your home) when it meets the atmosphere unless you do something about it prior to that. So long story short, radon in the water will contribute to radon in the air in your home but generally, most of the radon in the air in your home is coming from the ground directly into the basement and less from water offgassing into the air of your home. Tackling radon in the air should be done at the basement level using standard procedures first. But I would be remiss to point out that say taking a shower with radon infused water will cause said radon to offgas in your face as it exists the shower head if you decide to not treat it. Is it a problem? I have no idea but I also don't want to find out. NH seems to think its a problem as they have limits in place for radon in water. Other states don't (probably becuase radon isn't generally a problem in those states anyway) and supposedly the EPA is going to set up official limits (someday).

You have two choices to deal with radon - aeration or gac filter. Aeration is the only method for very high levels - look to NH limits for that and supposedly aeration for radon is a common thing there ( I don't know, don't live there). For lesser levels, you could use GAC as you indicate but over time you will collect the radon that eventually decays to other radioactive isotopes so your GAC filter can become concentrated radioactive waste if not careful (say if left in service for 10 years). I have radon at about the level you note and have decided to switch out the carbon every 2 years to purpsefully keep any concentrated radioactive source benign. This thread toward the end (posts 13 and onward) discusses this:

https://terrylove.com/forums/index.php?threads/system-review-and-sourcing-5810.93806/

One last thing, have you tested your ground water for gross alpha? If you research the 4 radioactive decay chains that I noted above, you will see that radon occurs in the middle of each chain. Which means you probably have various amounts of all the other radioactive isotopes in those chains in your ground and thus also in your groundwater. Radon may be the least of your concerns with the groundwater. Ask me how I know You can search my user name for other posts on this but I wouldn't be at all surprised if you ended up finding an elevated gross alpha as well as uranium and radium in your ground water becuase they are some of the long lived radioative isotopes in the 4 decay chains that include radon. You can't get radon without the other elements coming and going in the decay chains so its a sure bet they are there. Just depends on how concentrated they are.