Radon in Water (What You Need to Know in 2023)

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If your drinking water is supplied by a private well, you’re at an increased risk of being exposed to radon.

Radon is a colorless, odorless, and tasteless radioactive gas that occurs when uranium in the earth breaks down.

Here, we’ve shared the important facts about radon in water, including what it is, where it comes from, and its effects on your health.

๐Ÿ“Œ Key Takeaways:

  • Radon is a naturally occurring gas that’s caused by the breakdown of uranium.
  • Underground water sources, such as wells and springs, are more likely than surface water to contain dissolved radon.
  • There are no signs of radon in water, so you should check your Water Quality Report, review the EPA radon map, or test your water for this contaminant if you’re concerned.

โ” What Is Radon In Water?

Radon is a gas that has no color, taste, or smell when it’s dissolved in water.

When uranium breaks down in the ground, radon is formed. Radon gas particles are commonly found in groundwater supplies because this gas is known to enter underground water sources, like aquifers and springs, and has no way to dissipate into the air.

Radon has numerous human health effects. It’s more dangerous to inhale than it is to drink in water, but if you have radon in your water supply, this gas can escape from the water and pollute your home.

Tap water contaminated with radon

๐Ÿšฐ How Does Radon Get Into Water?

Radon gets into water from decaying uranium in the ground. When uranium breaks down, radon gases are released, which travel into underground sources of water and dissolve into the water.

When water containing radon enters your home, the gas has a chance to escape. Showering in radon-contaminated water or even simply switching on a faucet will cause radon gas to dissipate into the air, increasing the radon concentrations in your home’s breathing air.

Radon in water is dangerous, but the health effects of breathing radon in your indoor air are even more pronounced.

๐Ÿ”Ž How To Know If Your Water Contains Radon

There are a few different ways to get an idea of your water’s radon content:

Testing Your Water

You can’t see, smell, or taste radon in drinking water, so the only way to know whether or not your water contains radon is to conduct a test.

We recommend buying a laboratory water test to get an accurate, thorough analysis of your water’s radon concentrations.

Your lab test results will tell you exactly how much radon your water contains, and whether this concentration exceeds safety regulations set by organizations like the Environmental Protection Agency (EPA).

You can also test your indoor air for radon, which identifies whether your water supply is releasing significant levels of radon into your home.

We’ve discussed testing for radon in more detail later in this guide.

Water testing data sheet report

Assessing Your Water Source

You can also get an idea of your water’s likelihood to contain radon by assessing your water source.

If you get surface water, such as river, lake, or stream water, the radon gas will likely have been released into the outdoor air before the water was piped to your home. So, you’re less likely to have radon-contaminated water.

If your water comes from a groundwater supply, like private wells or springs, the radon gas won’t have had the opportunity to dissipate into the air while underground, which means it’s more likely for radon to be released into the air inside your home.

Viewing Your Water Quality Report

You’re responsible for testing and treating your water for radon if you own a private well. But if you’re on a public water system, your local water utility should monitor your water supply for radon and reduce radon levels when necessary.

You can contact your local authority for more information about drinking radon in public water or check your latest Water Quality Report (Consumer Confidence Report) to see if this contaminant was detected.

Viewing A Radon Contamination Map

Owners of private wells can also learn more about the likelihood of local radon groundwater contamination by reviewing the EPA’s map of radon zones in the USA.

This map doesn’t tell you for certain whether your water contains radon. But it does give you an idea of whether or not your home’s indoor air is likely to be contaminated with radon based on the levels of radon detected in your local area.

The map shows three radon zones:

  • Zone 1 (red) – highest potential for radon contaminationin levels greater than 4 pCi/L
  • Zone 2 (orange) – moderate potential for radon contamination in levels between 2 and 4 pCi/L
  • Zone 3 (yellow) – lowest potential for radon contamination in levels less than 2 pCi/L

Use the map for guidance only. If you drink private well water, you should test it for radon regardless of whether or not your home has a high potential for radon indoor air contamination.

EPA radon contamination map
Source: United States Environmental Protection Agency (epa.gov)

๐Ÿšฑ Is Radon In Drinking Water Dangerous?

Yes, radon in drinking water is dangerous. The biggest reason for this is that radon escapes from faucets, showers, and other water outlets and contaminates your indoor air. Airborne radon is highly dangerous and has several known health effects.

Lung cancer is one of the most serious health concerns linked to airborne radon. Breathing radon in the air generally increases your risk of developing internal organ cancers, like stomach cancer.

The EPA estimates that around 20,000 people die every year from being exposed to radon in the air.

There aren’t many studies on the health effects of drinking water containing radon, so we’re still unaware of exactly how ingesting radon in water might affect the human body.

Related: Does reverse osmosis remove radon?

๐Ÿ“‰ Is Radon In Tap Water Regulated?

No, there isn’t currently a federally-enforced regulation for radon in drinking water.

The EPA did propose to introduce a Maximum Contaminant Level (MCL) of 4,000 pCi/L (picocuries per liter) for radon, which will likely release around 0.4 pCi/L of radon gas into your home’s air, but this has yet to be officially enforced.

However, many states have indoor air programs for radon, which are approved by the EPA. Under the EPA’s proposed regulations for radon, the organization planned to set a lower MCL of 300 pCi/L for radon in water in states that didn’t have indoor air programs for this contaminant.

Testing water quality

๐Ÿงช How To Test For Radon In Tap Water

As we mentioned earlier, radon is an invisible contaminant, so the only way to know for sure that it’s in your water is to test for it.

We recommend two testing types for detecting radon in your home:

Laboratory Water Test

A laboratory water test will tell you exactly how much dissolved radon your water supply contains – although it won’t tell you how much of this radon has dissipated into the air in your home.

To conduct a laboratory radon test, follow these easy steps:

  1. Order a test from your preferred laboratory.
  2. Wait for the kit to arrive in the post.
  3. Take a sample or two of water in the included vials, then post the test back to the laboratory.
  4. Wait for the results to be posted or emailed to you (usually within 2 weeks).

Remember that a laboratory test will only give accurate results for a certain moment in time, so this form of testing doesn’t account for fluctuating radon levels in your water.

The radon levels in the soil and rocks surrounding your well aquifer may increase or decrease naturally over time. That’s why the Environmental Protection Agency suggests testing your well water for radionuclides (including radon) at least once every three years.

Getting tap water tested with tapscore

Indoor Air Test

Since radon released into the air is thought to be more dangerous than radon in water, we also recommend conducting an indoor air test for your home’s radon levels in the air.

You can start with an indoor air test if you prefer. Then, if your results are high, you can follow up by testing your water to see if it’s the source of your radon exposure.

Most radon air tests are designed to test the air in your home over a period of three months. To use these test kits, here’s what to do:

  1. Order your radon air test online.
  2. You will receive 2 radon detectors. Place one in your bedroom and one in your living room.
  3. Over the next 3 months, the radon detectors will take readings of your home’s radon levels.
  4. Return the radon detectors to the supplier and wait for the test results to be analyzed by the laboratory.
  5. Receive your test results within 10 days via email. The results will also advise you on further action that’s needed (if necessary).

Elevated radon levels in the air doesn’t necessarily mean that your water is to blame. However, if you do get your ground water from a private well, there’s a good chance that your water is at least contributing to the problem.

๐Ÿ‘ฉ๐Ÿฝโ€โš•๏ธ What To Do If You’re Concerned About Radon In Your Water

If you’ve discovered radon in your water, you may or may not need to take action, depending on your personal situation:

  • If you get your water from a municipal supplier, you shouldn’t have to do anything. Your water utility should take action to reduce radon in the local public water system.
  • If your water is supplied by a private well, check the EPA radon map and (if you haven’t already) test your water and air for their radon concentration.
  • If your test results for radon are high, you can reduce the radon level in your water with a suitable treatment system. Learn more in this guide on how to reduce radon in drinking water.
  • Once you’ve taken the necessary action to protect your family from radon in your home, you can retest your air and drinking water supply to make sure the solution you’ve implemented is working effectively,

โš ๏ธ Other Ways You Might Be Exposed To Radon

Aside from your drinking water, there are other potential sources of radon exposure:

  • Through cracks and holes in your home. Radon released by rocks and soils beneath your home may enter through small gaps and holes, gradually building up to dangerous levels.
  • Through smoking. Tobacco products treated with fertilizer containing radon increase your personal radon exposure when cigarette smoke is inhaled. Being exposed to secondhand smoke from a smoker also increases your radon exposure.
  • Certain occupations. Occupations such as mining increase a person’s likelihood of being exposed to radon, as do occupations that are carried out in underground workplaces in known radon-affected areas.
How radon gets into water

๐Ÿ“‘ Final Word: Removing Radon From Water

So, we know that radon in drinking water is dangerous, that it may cause radon gas to be released in your home, and that it’s linked to thousands of lung cancer deaths per year.

But what can we do about drinking water radon?

There are several at-home water treatment systems that offer an effective radon removal solution, including:

Both of these can be installed in a suitable location to remove radon dissolved in your drinking water before it can enter your home.

Staying safe and protecting your family from radon is possible – you just need to be vigilant and test for this radioactive gas regularly, and take suitable steps to remove it from your drinking water if necessary.

  • Brian Campbell
    Founder, Water Treatment Specialist

    Brian Campbell is a water treatment specialist and water expert based in Denver, Colorado. He's always been obsessed with water quality, and has spent years testing all kinds of treatment devices from simple pitchers and portable devices to complex whole home systems.

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