Arnold sits in Jefferson County, Missouri, and local water information describes naturally occurring radium and radon as part of the regional picture. If your home in Arnold runs on a private well, radon deserves a deliberate test rather than an assumption. This guide explains what radon is, how it reaches a home, and how to sample and read results without guessing.
What radon is and where it comes from
Radon is a naturally occurring radioactive gas. It forms as radium breaks down, and radium is found in some rock and soil. Because radon is a gas, it can move through groundwater and dissolve into the water that reaches your faucets. When that water runs in a shower, a washing machine, or a sink, some of the gas can escape into indoor air.
Radium behaves differently. It stays dissolved in water and has to be measured separately in a laboratory. A well owner usually needs to think about two things: the radon in the water and the radon level in the indoor air of the house.
Why a private well in Arnold deserves a closer look
Homes on public water in Arnold rely on the utility report for routine information. A private well has no such report, so the owner is responsible for sampling. Results can vary with well depth, the aquifer, and the rock the water passes through. Two wells on the same street can differ, so a neighbor's result is only a starting point.
Testing the water
Start with a water sample sent to a laboratory that is accredited for drinking water analysis. Ask the lab specifically for radon in water and, if the well may carry radium, a separate radium test. Home kits can offer a rough sense of conditions, but a laboratory result is the one to rely on for decisions.
Follow the lab's collection instructions closely. Radon is a gas and can escape from a sample that sits open or is handled poorly, so containers and timing matter. Ask whether the lab wants a sample taken from a cold tap before the water passes through any treatment, and keep the sample cool on the way to the lab.
Air testing is a separate step
A water result does not tell you the indoor air level. Short-term radon air test kits are available for homes and are commonly placed in the lowest livable level. Keep the kit where the instructions direct, set up the house as the instructions describe, and maintain normal water use in the days before the test so the reading reflects everyday conditions.
Reading results without panic
Lab reports list a detection level, a measured value, and notes from the lab. Read all three. A result above the detection level is not automatically a emergency, and a result below the reporting limit does not prove the water is free of the substance. Compare results against the standards and guidance published by the agencies that govern drinking water in Missouri, and keep copies with your well records.
Common next steps
- Confirm an unexpectedly high water result with a second sample.
- Test indoor air separately if the home uses well water for showers or laundry.
- Ask a qualified water professional to explain treatment options that fit your specific results.
- Retest after any change to the well, the pump, or treatment equipment.
Treatment choices depend on what the lab found. Radon in water is often addressed with aeration, which lets the gas escape before the water reaches the home. Radium is generally handled by a different process, such as ion exchange or reverse osmosis. These methods are not interchangeable, so match equipment to your test data rather than to a general label. Ask any professional to show you the results they used to size a system.
A note for homes in the south and west
Lead and other heavy metals are a separate concern for some private wells in the southern and western parts of Arnold, which are tied to the SW Jefferson County Mining Superfund area. If your well is in one of those areas, add a lead test to the same sampling visit. Lead is not part of a standard radon screen, so ask the lab to include it by name.
Keep your records together
Store every lab report, the date you sampled, the sampling location in the house, and any treatment change in one folder or file. When you sell or refinance, those records help explain the water history. They also let you compare future tests with past results, which is more useful than any single reading.