Radon in water: town supply and private wells in Mansfield
Radon dissolves in groundwater and comes out into the air when you run the shower or the dishwasher. Whether you need to think about it depends on where your water comes from.
Where Mansfield’s town water comes from
Mansfield’s public water is groundwater. According to the town’s annual water quality report, it’s pumped from wells and a wellfield in East and West Mansfield, and several well sites feed treatment plants that remove iron and manganese before the water goes into the mains. The town also has interconnection agreements with Easton, Norton, and Foxborough.
If you’re on town water, the town’s annual water quality report is the place to see what’s monitored. Questions about the public supply go to the town’s Water Division, not a radon contractor.
Private wells are a different story
A private well has no utility testing it for you. Radon levels in well water depend on the rock the well draws from, and they can vary a lot between neighboring wells.
If your house has its own well, test the water once, the same way you’d test the air. A water radon test uses a special vial filled carefully with no air bubbles, then sent to a lab. The sampling matters, so follow the lab’s instructions exactly or have a certified measurement professional take it.
How radon gets from water into the air
Radon is a gas, so it comes out of water when the water is agitated or heated. The shower, the washing machine, and the dishwasher are the big ones. That released gas adds to whatever is already coming up through the slab.
For most houses, soil gas is still the bigger source. Water tends to matter when the well reading is high and the house air stays stubborn after a sub-slab system is in.
How water systems remove radon
There are two common approaches for a private well.
- Aeration. Water runs through a tank where air is bubbled or sprayed through it. The radon comes out and is vented outside above the roof. This handles high levels well and is the usual choice when the reading is high.
- Granular activated carbon. A carbon tank holds onto the radon as water passes through. It’s simpler, but the carbon itself becomes radioactive as it collects radon and may need shielding and special disposal. It’s generally used for lower levels.
A certified mitigation professional can tell you which fits your reading. See how to find one, or go back to the Mansfield radon guide.
Water questions
Is radon in water dangerous to drink?
The main concern with radon in water is the gas it releases into the air of the house, which you then breathe. Drinking it carries a smaller risk. Both are reasons to test a private well.
Does the town test for radon?
Check the Town of Mansfield's annual water quality report for the contaminants it monitors and what treatment each well site gets. Questions about the town supply go to the Water Division.
My air test was high. Is it the water?
Usually not. Soil gas under the slab is the main source in most houses. If you're on a private well and the air stays high after a mitigation system, test the water.
- We don't sell tests or install systems
- Every figure links to its source
- Built on Massachusetts DPH and EPA guidance