Private Well Water Testing in Wisconsin

County-by-county USGS area-risk estimates for private wells across Wisconsin — arsenic exceedance probability and private-well population — plus how to test your own well at a Wisconsin-certified laboratory.

Wisconsin private-well risk summary

Counties covered

Wisconsin counties with modeled risk data.

People on private wells

area estimate

1,519,944

estimated across covered Wisconsin counties.

Average arsenic risk

area estimate

average modeled chance a well exceeds 10 µg/L arsenic across covered counties.

Wisconsin counties

Find a Wisconsin-certified testing lab

Get your well tested at a Wisconsin-certified laboratory. We list certification programs by state.

Wisconsin certified labs

Already tested your well? Get a free plain-English reading

Upload your well water lab report (PDF or a photo) and our team will email you a full, plain-English reading of every result — free. Educational only, never medical advice.

Your upload also helps us keep local water data accurate — we only ever share anonymized, area-level summaries.

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These figures are USGS area estimates: statistical groundwater models describing how likely elevated contaminant levels are across a county. They are not designed to predict the concentration in any single well. Only testing your own well reveals its water quality.

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By TapWaterData Editorial