Well Water Testing Requirements in Wisconsin (WI)
Wisconsin requires well water testing at property sale for bacteria and nitrate under Wisconsin Statute 280.05. The state has approximately 800,000 private wells. The Wisconsin DNR manages well programs. Nitrate contamination from agriculture is widespread, and naturally occurring radium is a concern in some sandstone aquifers. The state has approximately 800,000 private wells.
Required Contaminant Tests in Wisconsin
Wisconsin requires testing for the following 2 contaminants at property sale:
Common Contaminants in Wisconsin Well Water
Based on geological conditions, land use patterns, and historical testing data, these contaminants are commonly found in Wisconsin private wells. Even if not required by law, testing for these contaminants is recommended.
Testing Requirements by City in Wisconsin
Local testing requirements may vary from state-level regulations. Some counties and municipalities have stricter rules than the state minimum. Below are details for major cities in Wisconsin.
| City | Testing Required | Notes |
|---|---|---|
| Milwaukee | Yes | Milwaukee County; mostly public water |
| Madison | Yes | State capital; Dane County |
| Green Bay | Yes | Brown County; Fox River area |
| Waukesha | Yes | Waukesha County; radium in sandstone wells |
| Appleton | Yes | Outagamie County; Fox Valley |
Testing Recommendations for Wisconsin Well Owners
- PFAS (forever chemicals) have been detected in your state. Consider testing for PFAS compounds.
- Nitrate contamination is common in your area. Test annually, especially if near agricultural land.
- Your state requires well water testing when selling property. Budget for testing costs in your sale preparation.
Understanding Wisconsin's Well Water Regulations
Testing Frequency
Wisconsin requires well water testing at property sale. This means that when a home with a private well is sold, the seller (or in some cases the buyer) must obtain water test results from a certified laboratory. The results must be provided to the buyer before closing. Beyond the sale requirement, regular testing is recommended but not mandated by the state.
New Well Requirements
Wisconsin requires testing when a new well is constructed or an existing well is significantly modified. The required tests include bacteria (coliform/e. coli), nitrate, and the well must pass these tests before being put into service for drinking water. Well construction must comply with state standards and a permit is required before drilling.
State Laboratory and Testing Resources
Wisconsin operates a state laboratory or participates in a state lab network that provides water testing services, often at subsidized rates below commercial laboratory prices. Contact your state health department or environmental agency for current pricing and sample submission procedures. Many county health departments also offer basic bacteria testing, sometimes at no cost. The average cost for a comprehensive well water test in Wisconsin is approximately $125, though a basic bacteria and nitrate screen may cost significantly less.
How Wisconsin Compares
Wisconsin has a moderate level of well water testing regulation. Below are other states with similar regulatory approaches.
| State | Testing Required | Test at Sale | Required Tests | Avg. Cost |
|---|---|---|---|---|
| Wisconsin (WI) | Yes | Yes | 2 | $125 |
| New Hampshire (NH) | No | Yes | 15 | $350 |
| Oregon (OR) | Yes | Yes | 3 | $200 |
Check Other States
Use our well water testing lookup tool to check requirements for any state, or browse all 50 states ranked by testing strictness. If you are moving to or buying property in Wisconsin, understanding the testing requirements is an important part of your due diligence.