Private Well Water Testing in Massachusetts
County-by-county USGS area-risk estimates for private wells across Massachusetts — arsenic exceedance probability and private-well population — plus how to test your own well at a Massachusetts-certified laboratory.
Massachusetts private-well risk summary
Counties covered
14
Massachusetts counties with modeled risk data.
People on private wells
area estimate430,742
estimated across covered Massachusetts counties.
Average arsenic risk
area estimate8%
average modeled chance a well exceeds 10 µg/L arsenic across covered counties.
Massachusetts counties
- Worcester County13% arsenic exceedance (area estimate)109,574 people on private wells
- Middlesex County14% arsenic exceedance (area estimate)50,963 people on private wells
- Plymouth County5% arsenic exceedance (area estimate)46,708 people on private wells
- Bristol County6% arsenic exceedance (area estimate)44,366 people on private wells
- Hampden County9% arsenic exceedance (area estimate)32,399 people on private wells
- Hampshire County7% arsenic exceedance (area estimate)25,019 people on private wells
- Barnstable County6% arsenic exceedance (area estimate)24,361 people on private wells
- Berkshire County4% arsenic exceedance (area estimate)23,846 people on private wells
- Franklin County6% arsenic exceedance (area estimate)21,520 people on private wells
- Essex County14% arsenic exceedance (area estimate)21,183 people on private wells
- Norfolk County9% arsenic exceedance (area estimate)19,376 people on private wells
- Dukes County6% arsenic exceedance (area estimate)5,027 people on private wells
- Suffolk County8% arsenic exceedance (area estimate)4,191 people on private wells
- Nantucket County6% arsenic exceedance (area estimate)2,209 people on private wells
Find a Massachusetts-certified testing lab
Get your well tested at a Massachusetts-certified laboratory. We list certification programs by state.
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Upload my well testThese 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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