Wait… Radon Can Be in Your Water Too?

January 17, 2026

Why Testing Your Well Water for Radon Matters in New Hampshire

When most people hear the word radon, they think of air tests, basements, and scary EPA charts. And while radon in air absolutely deserves attention, there’s another place radon likes to hide—one that often surprises New Hampshire homeowners:

👉 Your well water.

If your home uses a private well (like many do in NH), radon in water testing is something you should not overlook—especially as part of a comprehensive NH home inspection or post-purchase safety check.

Let’s dive in (pun fully intended 💧).

What Is Radon in Water?

Radon in water comes from the same natural source as radon in air—uranium in soil and bedrock. In New Hampshire, groundwater flowing through granite and bedrock can pick up radon before it ever reaches your faucet.

You can’t see it.
You can’t smell it.
You definitely can’t taste it.

But when that water is used for:

Showering
Laundry
Cooking
Dishwashing

Radon can be released into the air inside your home, contributing to overall radon exposure.

When Should You Test Your Water for Radon?

Testing is recommended if:

✔ Your home uses a private well
✔ You are buying or recently purchased a home
✔ You’re doing NH radon testing for air already
✔ You’ve never tested the water before

Unlike radon in air, radon in water levels are fairly stable year-round, so testing can be done at any time of year.

Many homeowners choose to test:

During a home inspection
Shortly after moving in
When upgrading filtration or treatment systems

Important (and Surprising) Truth

Radon in Water ≠ Radon in Air

This is one of the biggest misconceptions we see during an NH home inspection:

High radon levels in air do NOT automatically mean high radon levels in water—and vice versa.

Why?

Radon in air depends on soil gas, foundation entry points, and ventilation
Radon in water depends on groundwater and bedrock conditions

You can have:

High radon in air and low radon in water
High radon in water and low radon in air
High in both (lucky you 🙃)
Low in both

The only way to know is to test each independently.

What Happens If Radon Levels in Water Are High?

The good news?
Radon in water is very treatable.

There are two common—and highly effective—radon water mitigation systems used in New Hampshire.

1. Aeration Systems

Radon Bubble-Up Systems

(The Most Common & Most Effective)

How it works:

Water enters a treatment tank
Air is bubbled through the water
Radon is released from the water and safely vented outside
Radon-free water continues into the home

Pros:

✅ Removes up to 99% of radon
✅ Highly effective for high radon levels
✅ Treats the entire home’s water supply

Cons:

❌ Higher upfront cost
❌ Requires space and professional installation

Best for: Homes with moderate to high radon levels in water

2. Granular Activated Carbon (GAC) Systems

Carbon Filter

(The Compact Option)

How it works:

Water passes through a carbon filter
Radon is trapped in the carbon media

Pros:

✅ Lower initial cost
✅ Compact size
✅ Simple design

Cons:

❌ Less effective for very high radon levels
❌ Carbon can become radioactive over time
❌ Requires regular monitoring and replacement

Best for: Homes with low radon levels in water

Why Water Testing Still Matters—Even If Your Air Levels Are Low

Radon released from water can:

Increase indoor air radon levels
Add to overall long-term health risk
Go completely unnoticed without testing

The EPA estimates that radon in water contributes thousands of lung cancer cases each year—not because it’s common knowledge, but because it’s often missed entirely.