If you draw water from a private well in St. Charles, or live near one, radium and uranium belong on your testing list. Both are naturally occurring elements found in bedrock, soil, and groundwater. Neither shows up by taste, smell, or color, so a clear glass of water tells you nothing about them.
What These Elements Are
Radium and uranium are radioactive elements that occur naturally in rock and sediment. As water moves through those materials, it can dissolve small amounts and carry them into a well. Radium forms as a decay product in the uranium chain, so the two often show up together in the same geology. Levels depend on the rock and sediment layers a well draws from, how deep the well is, and how water moves underground, so two neighboring wells can produce very different results.
Why Local Geology Matters in St. Charles
Many private wells in and around St. Charles tap the Missouri River alluvial aquifer, a layer of river-deposited sand and gravel that is closely connected to the river. That setting means local water quality can change from one property to the next. The area also includes the Weldon Spring site, a documented legacy site from former federal processing work. Living near a documented site does not mean a particular well is affected, and it does not mean the water is safe. It is a reason to test rather than assume.
What a Test Should Include
A general well panel often does not cover radioactive elements, so ask the lab by name for the specific tests you want. Common requests include radium analysis and total uranium. Some labs run a gross alpha screen first, which flags whether more detailed radium testing is worth doing. Confirm with the lab which container, preservative, and sample volume it requires, since these vary, and ask how long the sample can wait before it reaches the lab.
Steps Before You Collect a Sample
- Find the well construction record, including depth and casing information, if you have it.
- Choose a laboratory that is certified or accredited by the state and lists radiological parameters.
- Collect the sample from a cold tap that is ahead of any treatment device, following the lab's instruction sheet exactly.
- Write down the date, the time, and whether the pump ran recently.
- Deliver or ship the sample within the window the lab specifies.
Reading the Results
A lab report lists each parameter with a reported value, a units column, and usually a detection limit or method note. Compare each result against the standard the report references, and ask the lab to explain any flag. A result below the detection limit is not the same as a confirmed absence, so ask how the lab handles those entries. Keep the full report, not just a summary sheet, because you may need it for a home sale, a lender, or a future comparison.
If Results Come Back Elevated
Treatment options exist, including ion exchange and reverse osmosis systems, but the right approach depends on which elements are present, the water chemistry, and how the household uses water. Some treatment media that removes radium can concentrate it, so ask how spent media will be handled and disposed of before any equipment goes in. Before buying anything, confirm the result with a second sample, since a single reading can reflect a temporary condition. Ask any provider for testing documentation before and after installation, and ask how the system will be checked over time.
Where to Get Local Help
Start with the St. Charles County health office, which can point you to local guidance on private well sampling. The state environmental agency also publishes material on testing private wells. If a neighbor draws from the same aquifer, comparing sampling dates and lab names can help you tell whether your results fit a broader pattern or stand apart from it.