If your St. Charles home runs on a private well, radon is one of the few household concerns that can show up in two places at once: the indoor air you breathe and the water you draw from the tap. Radon is a naturally occurring radioactive gas that forms when uranium breaks down in soil and bedrock. It has no color, no odor, and no taste, so only a test can tell you whether it is present in your home.
Why radon shows up in St. Charles homes
Radon moves up through soil and enters a house through cracks in the foundation slab, gaps around pipes, sump pits, and construction joints. Homes tend to pull air in from the ground when indoor air pressure is lower than the pressure in the soil around the foundation. That pattern is common in closed, heated houses during colder months, when windows stay shut and exhaust fans run.
Water can carry radon as well. Groundwater pulled from wells can hold dissolved radon, and the gas escapes into the air when that water runs through a shower, a washing machine, or a sprayer faucet. In other words, a well can add radon to indoor air even when the soil under the house is not the main source.
The local setting matters too. Public water reports for the area describe a mix of river water and groundwater, and private wells nearby draw from the Missouri River alluvial aquifer. Naturally occurring radium and uranium are part of the regional picture, and those concerns are amplified near the Weldon Spring legacy site. Your own well and your own home are the only sources that matter for your decisions, so a test on your property is more useful than assuming a neighbor's results apply to you.
Test the air first
Air testing is usually the simpler starting point. Short-term test kits are sold at many home and hardware stores, and some homeowners prefer a longer test that runs across a full season. Either way, a few habits make a result more reliable:
- Test in the lowest level of the house that you actually use for living, such as a finished basement or a ground-floor room.
- Keep windows and exterior doors closed during the test, except for normal entry and exit.
- Keep your heating and cooling running as usual, and do not change fan settings for the test.
- Place the device away from drafts, sinks, and direct sunlight, and keep it off the floor and away from exterior walls.
- Follow the kit instructions exactly, then mail or send the device to the lab named in the kit. Keep a copy of the paperwork with the date and location of the test.
Test the water
Water testing requires a laboratory, not a simple home kit. Look for a lab certified for drinking water testing, and ask whether it can run radon in water. If you are also concerned about the local mineral picture, ask whether radium and uranium can be included in the same order.
- Request the sample kit and read the collection instructions before you open anything.
- Collect the sample from the cold tap you use for drinking, following the lab's guidance on running the water beforehand.
- Fill the container slowly to limit bubbles, since radon can escape from water when it is agitated.
- Write down the date, the time, and any recent work on the well, pump, or pressure tank.
- Send or deliver the sample promptly, following the lab's timing rules.
Reading the results without guessing
A lab report lists a measured level for each substance, along with the unit used and a guideline or reference value. Compare your results against the guideline printed on the report, and ask the lab to explain anything that is unclear. Avoid comparing a single air result with a neighbor's reading, because levels can shift from room to room and from season to season.
If a result is above the guideline, the sensible next step is a repeat test under the same conditions. If the repeat confirms the concern, talk with a qualified professional who works with radon and well water systems. That person can explain the options that fit your specific house and well, and you can compare those options on your own terms.
When to test again
- After any foundation repair, crack sealing, or basement finishing work.
- After a well pump, pressure tank, or treatment system is replaced.
- After a major flood or a stretch of heavy rain in the area.
- When you buy a home, and at regular intervals after that.
- When the way the house is used changes, such as when a room is converted to living space.
What to do this week
If you have never tested your St. Charles home for radon, start with the air. Once that is underway, and if you have a private well, order a water sample at the same time so the two results can be read together. Keep all the paperwork in one folder, with the date and location of each test. Testing is the only reliable way to know your own levels, and a clear record makes every later decision easier to understand.