Well water testing checklist
Private well owners are responsible for their own testing. Here's what the Wisconsin DNR recommends.
| ✓ | Test | How often | WSLH price* |
|---|---|---|---|
| Bacteria (total coliform / E. coli) | Every year, and whenever taste, color or smell changes | $35 | |
| Nitrate | Every year, and before use by someone who is or may become pregnant, or for an infant | $35 | |
| Arsenic | Every 5 years for most wells; every year in Outagamie, Winnebago or Brown counties, or after a previous arsenic result | $38 | |
| Homeowner package (bacteria, nitrate, metals, hardness, VOCs, atrazine) | Optional, when buying a home or troubleshooting | $450 |
*Wisconsin State Laboratory of Hygiene price list, checked Nov 5, 2026. Other certified labs and county health departments may charge less or more.
When results come back
- Bacteria present: stop drinking the water (DNR).
- Nitrate over 10 mg/L: don't give it to infants under 6 months or use it for formula, and avoid it if pregnant (DNR).
- Arsenic over 10 µg/L: DHS recommends not using it for cooking foods that absorb a lot of water.
- Get the sample to the lab within 48 hours, and follow the kit's directions to avoid false positives.
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Official links
- WI DNR: Test your private well water annually
- WI DNR: Tests for Private Well Users (DG-023, PDF)
- Wisconsin State Laboratory of Hygiene: test kit ordering and prices
- WI DNR groundwater FAQ
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