Private Well Water Testing in Ohio

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

Ohio private-well risk summary

Counties covered

Ohio counties with modeled risk data.

People on private wells

area estimate

1,823,086

estimated across covered Ohio counties.

Average arsenic risk

area estimate

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

Ohio counties

Find a Ohio-certified testing lab

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

Ohio 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