Most St. Charles well owners start with bacteria, nitrate and iron, and those are worth testing. Radium and uranium get less attention, but both are naturally occurring elements that can be present in groundwater, and the St. Charles area is one where they are worth asking about. Near the documented Weldon Spring legacy site in St. Charles County, these naturally occurring elements can be more pronounced in some wells, so a homeowner there has good reason to ask the question directly rather than assume the answer.

What radium and uranium are

Radium is a naturally occurring element found in some rock and soil. Uranium is also naturally occurring and can dissolve into groundwater as water moves through the materials around it. Neither one has a color, taste, or smell, so a clear glass of water tells you nothing about what it contains. A lab test is the reliable way to know.

Why local wells deserve a specific question

Private wells in and around St. Charles tap the Missouri River alluvial aquifer, a body of water that moves through sand and gravel deposits. The minerals in that water reflect the materials it passes through, and two wells a short distance apart can carry different results. Public water reports for St. Charles describe a mix of river and groundwater sources for the municipal supply, which is a separate system from a private well. A well owner is responsible for their own testing, so a general city report does not answer the question for a private well.

When to test

Consider a radium and uranium test if any of these apply:

  • You have never had your well tested for these elements, or the record is unclear.
  • Your property is near the Weldon Spring legacy site, or you are unsure how far it sits from that area.
  • You are buying a home with a private well and want the water quality documented before closing.
  • Other well results have changed, or you notice a shift in appearance or taste that you cannot explain.

How to sample

Use the sample container and instructions from the laboratory you choose, because the lab knows which preservatives and holding times it needs. The general approach is consistent:

  1. Call the lab and confirm which radium and uranium methods it runs and how it wants the sample collected.
  2. Collect water from a cold tap, ideally before any treatment equipment, so you see the raw well water.
  3. Let the water run until the line clears, then fill the container without touching the inside of the bottle or the cap.
  4. Label the container, record the date and time, and ship or deliver it within the window the lab specifies.

Reading the results

A lab report lists each element with a result, a units label, and a reporting limit. Compare the result to the standard the lab cites, and note whether the result is above or below that standard. Ask the lab to explain any term you do not recognize. A result reported as below the reporting limit means the lab did not detect the element at that level, which is different from saying the element is absent from the water.

What to do with the result

  • Keep the full report with your home records, since it becomes a baseline for future testing.
  • If a result is above the standard, talk with a qualified water professional about options, and ask them to explain their reasoning before any equipment is recommended.
  • Retest on the schedule your lab or water professional recommends, and retest after any change at the well or around the property.
  • Do not start treatment based on guesses. Test first, then match the response to the results.

Questions to ask before you order

  • Does the lab run radium and uranium on the same sample, or are they sent separately?
  • What units and reporting limits appear on the report?
  • How long can the sample sit before it reaches the lab, and what happens if the window passes?

Testing gives you a fact to work from. In St. Charles, where the aquifer and local geology create real differences between properties, that fact is worth more than a neighbor's opinion or a general rule.