A private well in Arnold needs a testing plan, not a single test. Water quality can shift with the seasons, with rainfall, with changes around the property, and with the age of the well and its equipment. A simple calendar helps a homeowner know what to check, when to check it, and when a result calls for a closer look.
Start with a baseline
If you have just moved in or have never had your well tested, begin with a full panel from a certified laboratory. Ask the lab to match the test list to what is known about groundwater in Jefferson County, MO. Keep the report with your home papers so future results have something to compare against.
Coliform and E. coli
Bacteria tests belong on the yearly list for any well, and more often for shallow or older wells. Sample after repairs, after flooding, and whenever anyone in the home notices a change in taste, odor, or clarity. A positive result is a reason to act and retest, not a reason to ignore the water.
Nitrates
Nitrate can move into groundwater from septic systems and nearby farm fields, and levels can change with the season. Follow the lab's sample handling directions closely. Testing right after heavy rain can show a storm-related change, so note the weather when you sample. Repeat testing across the year shows whether levels move with the season.
Lead for wells in the south and west
Well owners in the south and western parts of Arnold should include lead in their testing plan. The Environmental Protection Agency is addressing lead and other heavy metals in private wells tied to the Southwest Jefferson County Mining Superfund area, so sampling for lead is a sensible step even if the water looks and tastes normal. Lead is a metal you cannot see, taste, or smell. Ask the lab which sampling method it recommends, and ask whether it wants a first-draw sample taken after the water has sat in the pipes overnight. Keep the results with your well records.
Hardness, iron, and sulfur
Hardness, iron and manganese, and hydrogen sulfide mostly affect appearance, fixtures, and equipment. Hard water leaves scale on fixtures and appliances. Iron and manganese stain laundry and sinks. A rotten egg smell points to hydrogen sulfide, and sulfate is often tested alongside it. Check these when you notice changes, and before choosing any treatment, since a test shows what actually needs treating.
Radium and radon
Radium occurs naturally in some groundwater and can show up in private wells. Radon is a gas that can dissolve in well water and also reach indoor air. Test the water and the indoor air separately, because each uses different methods, and the two results should not be mixed together when you read them.
A simple calendar
- Each year: a bacteria test and a basic chemistry panel that includes nitrate.
- Each year in the south and west: lead.
- After flooding, heavy rain, or well repairs: bacteria and any test tied to the change.
- When you notice a change: the test that matches what you see, smell, or taste.
- Every few years: review the full list with your lab or a trained well professional.
Keep your records
Store every report in one folder or file, with the date, sample location, and lab name. Note any repair, new fixture, or change in the household. A few years of results make trends easy to see and make the next decision clearer.
Before you act on a result
A single result is a snapshot. Retest before making a large decision, and confirm that the sample was taken the way the lab asked. If results are unclear or concerning, talk with your lab about next steps and ask which fixes address the specific test that failed.