Private Well Water Testing in Arizona
County-by-county USGS area-risk estimates for private wells across Arizona — arsenic exceedance probability and private-well population — plus how to test your own well at a Arizona-certified laboratory.
Arizona private-well risk summary
Counties covered
15
Arizona counties with modeled risk data.
People on private wells
area estimate236,963
estimated across covered Arizona counties.
Average arsenic risk
area estimate22%
average modeled chance a well exceeds 10 µg/L arsenic across covered counties.
Arizona counties
- Maricopa County48% arsenic exceedance (area estimate)42,895 people on private wells
- Yavapai County25% arsenic exceedance (area estimate)40,731 people on private wells
- Pima County42% arsenic exceedance (area estimate)26,674 people on private wells
- Cochise County9% arsenic exceedance (area estimate)22,281 people on private wells
- Pinal County40% arsenic exceedance (area estimate)20,660 people on private wells
- Apache County11% arsenic exceedance (area estimate)14,994 people on private wells
- Navajo County11% arsenic exceedance (area estimate)12,472 people on private wells
- Mohave County15% arsenic exceedance (area estimate)11,197 people on private wells
- Yuma County39% arsenic exceedance (area estimate)10,812 people on private wells
- Gila County8% arsenic exceedance (area estimate)8,344 people on private wells
- Coconino County11% arsenic exceedance (area estimate)7,500 people on private wells
- La Paz County33% arsenic exceedance (area estimate)6,165 people on private wells
- Graham County12% arsenic exceedance (area estimate)5,655 people on private wells
- Santa Cruz County6% arsenic exceedance (area estimate)4,582 people on private wells
- Greenlee County15% arsenic exceedance (area estimate)2,001 people on private wells
Find a Arizona-certified testing lab
Get your well tested at a Arizona-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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