Only 1 health check had enough tested wells in Harrison County, and it came back rare.
The only health check here came back rare.
From 128 wells tested in Harrison County since 2000; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: nitrate (2), arsenic (2), uranium (2), radon (2), lead (2), fluoride (2).
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
1 in 9 people 24,532 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
How deep wells go here
Deep wells: fewer surface germs, more minerals from the rock.
Well depths: US Groundwater Well Database
Radon risk (a gas from rock)
Less likely, but the EPA still says test your air.
Radon zones: EPA map
Here's how Harrison County compares with Mississippi and the counties around it.
Each result puts Harrison County next to the 5 counties that border it, on the chart's 0 to 50% scale.
The only health check in Harrison County is rare.
Manganese2 of 128 wells over
Too few Harrison County wells were tested for these 6.
Nitrate2 wells tested
Arsenic2 wells tested
Uranium2 wells tested
Radon in water2 wells tested
Lead2 wells tested
Fluoride2 wells tested
None of the 2 Harrison County wells tested for bacteria had it, but every well needs a yearly test.
Coliform bacteria0 of 2 wells had it
E. coli0 of 2 wells had it
E. coli means human or animal waste is getting in, so if a test of your Harrison County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 11 of 128 tested wells, and it isn't a health risk.
Iron stains11 of 128 wells had it
Harrison County has 128 tested wells, and the busiest decade for testing was the 2000s.
None of the 128 wells has a test from 2020 or later, so a fresh test of your own well tells you more than any of these.
Most Harrison County wells in these records were tested for research or because someone suspected a problem, which can push the shares above what a typical home well would show (how we read the numbers).
One mail-in lab test covers the 3 things to check in Harrison County.
- Bacteria
- Nitrate
- Arsenic
What Mississippi offers well owners
- Free testingWe didn't find a free program for all of Mississippi. Mississippi's private well page
- Certified labsMississippi's list of certified labs
- Well recordsWe didn't find an online search.
Half the household wells here are shallower than 357 feet.
That comes from 8,319 household wells in Mississippi's drilling records. Most wells of every kind here are 240 to 516 feet deep. Wells as deep as Harrison County's are usually better protected from fertilizer and bacteria at the surface, but they can pick up more of what's in the rock, like arsenic and uranium. Typical household wells here go deeper than in 65 of the 81 other Mississippi counties with enough drilling records.
How to find your own well's depth
Well depths: US Groundwater Well Database
Here's what we know about radon and PFAS in Harrison County.
Harrison County is in the EPA's lowest radon zone, so radon from well water is unlikely to be a problem. Radon guide
Between 2023 and 2025 the EPA had 11 town water systems in Harrison County test for PFAS. 1 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 7.7 ng/L of PFOS. No well in Harrison County has public PFAS results, so the town systems are the best clue to what's in the groundwater nearby. PFAS guide
Radon zones: EPA Map of Radon Zones. PFAS: EPA tests of town water systems, 2023 to 2025
Questions people ask about well water in Harrison County
Is well water in Harrison County safe to drink?
Most tested wells in Harrison County came in under the limits. Of 1 health check with enough tests, manganese came closest, at 2 of 128 wells over. Every well is different, so test yours for bacteria, nitrate and arsenic.
Where can I get my well tested in Harrison County?
Use a lab Mississippi has certified for drinking water. Mississippi's list is linked above, in the box about testing. Ask for bacteria, nitrate and arsenic, the tests that matter most in Harrison County.
How deep are wells in Harrison County?
Half the household wells here are shallower than 357 feet. Typical household wells here go deeper than in 65 of the 81 other Mississippi counties with enough drilling records.
How often should I test my well in Harrison County?
None of the 2 wells tested for bacteria in Harrison County had it, but the CDC still says to test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.
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Where the Harrison County numbers come from
- People on wells: 24,532 in Harrison County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 759 well water samples from 128 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2015.
- Well depths: 8,319 Mississippi drilling records for Harrison County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 5 counties that share a border with Harrison County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 11 town water systems in Harrison County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Harrison County is zone 3 on the EPA Map of Radon Zones.
- State programs and links: Mississippi State Department of Health, checked November 1, 2026.