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Well water testing in Union County, Mississippi

What official data says about private wells in Union County, what to test for, and the state-certified labs nearby.

People on private wells (2015)6,042

About 21% of the county's 28,429 residents. Rank 26 of 82 in Mississippi.

Arsenic above EPA’s limit (USGS estimate)about 46 people

95% range 34 to 63 private-well users (2010 base year). Rank 16 of 82 in Mississippi.

EPA radon zone (indoor air)Zone 2

Moderate potential (average indoor radon may be between 2 and 4 pCi/L). EPA says the map should not be used to decide whether an individual home needs testing.

Certified labs in this county0

Labs with an address in this county, from the official state lists on this site, matched by ZIP code.

What to test for in Union County

Private wells are not regulated like public water: EPA advises owners to test their well every year for total coliform bacteria, nitrates, total dissolved solids and pH. Your state's own schedule:

  • Mississippi State University Extension recommends testing private drinking water wells at least once a year. source

Arsenic. USGS estimates that about 46 people using private wells in Union County had arsenic above 10 µg/L, EPA's limit for public water (2010 base year; 95% range 34 to 63). USGS describes this kind of estimate as useful "for broad screening of the population at risk", so it says nothing certain about any one well. Arsenic has no taste or smell: test for it by name.

Radon. EPA puts Union County in Zone 2: moderate potential (average indoor radon may be between 2 and 4 pCi/L). That map is about radon in indoor air, and EPA says it should not be used to decide whether an individual home needs testing. If radon is found in your air and you have a well, EPA suggests testing the water too: see radon in well water.

For anything specific to your home (farms nearby, old plumbing, a new baby, a smell or stain), use the which-tests checklist. When the results arrive, check your numbers against EPA's limits.

Estimated private-well users with arsenic above 10 µg/L: Union County and Mississippi's highest countiespeople (2010 base year)
Show the numbers
ItemValueNote
Jackson County309 people (2010 base year)
Harrison County275 people (2010 base year)
Marshall County213 people (2010 base year)
Washington County149 people (2010 base year)
Tate County146 people (2010 base year)
Union County (this county)46 people (2010 base year)

USGS model estimate for broad screening, not a measurement of any well. Only a test tells you about your own well. Source: USGS, Estimated county level domestic well population with arsenic greater than 10 micrograms per liter (Ayotte, Medalie and Qi, 2017), accessed 2026-11-01.

PFAS in public water near Union County (public supply, not your well)

This is public water data, not your well. A private well draws its own groundwater, which can have more or less PFAS than the public supply nearby. Only a test of your well tells you.

Under EPA’s fifth Unregulated Contaminant Monitoring Rule (UCMR 5), public water systems sampled their water for 29 PFAS between Jan 3, 2023 and Jun 17, 2026. 3 public systems that serve ZIP codes mainly in Union County reported results. 0 of them had at least one sample with PFOA or PFOS at or above 4.0 ng/L, and 0 had at least one of the 29 PFAS measured at or above its reporting level.

4.0 ng/L (parts per trillion) is both EPA’s UCMR 5 reporting level for PFOA and PFOS and the number in EPA’s 2024 limit for public water. That limit is judged on a running annual average, so one sample at that level is not a violation. EPA proposed changes to its PFAS rules in May 2026: see PFAS in well water for the current status and who should test a well. To test your own well, find a lab certified for PFAS.

Method: a system counts for this county when it reports serving a ZIP code whose largest land part is in this county, so a system serving several counties counts in each. Source: U.S. EPA, UCMR 5 occurrence data (by state), file dated Oct 15, 2026; downloaded Nov 1, 2026.

Testing programs and help in Mississippi

  • A Mississippi State Department of Health (MSDH) environmentalist can visit your well and take a sample, which the state lab in Jackson tests for total coliform. There is a fee; contact the MSDH Division of On-Site Wastewater. source
  • Mississippi State University Extension's Mississippi Well Owner Network is another option for well owners who want water testing. source

Buying a home with a well in Union County

Loan test (FHA, VA, USDA) in Union County, MS

  • VA. Test results are valid for 90 days from the date the local health authority certifies them, unless the local authority says otherwise. VA’s chapter names no list of contaminants: the water must meet the local health authority’s requirements, or EPA guidelines where it has none. Your lender may ask for specific tests.
  • FHA. A well test is required in the situations FHA’s handbook lists, among others, and the report may not be more than 180 days old at disbursement.
  • USDA. Guaranteed loans need a water quality test for a private well, done by the local health authority or a state-certified lab, and no more than 180 days old at closing.

Lenders can ask for more (extra tests, a particular lab, who takes the sample): ask your lender before you book. Federal rules as read on Nov 3, 2026 source 1 source 2 source 3. Full comparison: VA, FHA and USDA well water test requirements. Loan test kits sold by mail, with price and days to results: kits compared.

State-certified labs in Union County

None of the labs on our Mississippi list has an address in Union County. Labs elsewhere in the state may take samples by mail or courier: ask the lab, and check the hold time for bacteria before you send one.

Labs on the Mississippi list whose own websites say they take homeowner samples: Bonner Analytical Testing, Inc. (Hattiesburg). Use Check my ZIP to sort labs by distance.

See all Mississippi labs in the finder and filter by the test you need and by labs that take homeowner samples.

Sources and method Private-well population is the USGS 2015 estimate of people on domestic self-supplied water. The arsenic figure is a USGS model estimate on a 2010 population base, not a count of tested wells. Labs are placed in a county by the ZIP code on the state list. These figures come from different USGS products, years and methods, so they can disagree with each other (for example, the arsenic estimate and the well population use different base years). Read them as context for the county, not as facts about any one well. Checked 1 Nov 2026. General information, not medical advice.
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