Private wells
Mississippi well water: who's on a well and what to test for
People on private wells
506,500
Homes on wells
17.3%
Est. above arsenic limit
2,800
Every Mississippi county
Sorted by people on private wells. Arsenic and nitrate are modeled for typical wells in the county, not measured at yours; depth is the median of domestic well records.
| Jackson County | 33,100 | 21% | 2.6% | 0.0 | 222 ft |
| Harrison County | 24,500 | 11% | 3.8% | 0.0 | 300 ft |
| Pearl River County | 23,700 | 42% | 2.4% | 0.1 | 190 ft |
| Marshall County | 20,400 | 62% | 2.8% | 0.1 | 150 ft |
| Rankin County | 17,400 | 9% | 2.4% | 0.0 | 196 ft |
| Lincoln County | 14,400 | 40% | 3.8% | 0.1 | 106 ft |
| Tate County | 13,500 | 51% | 2.1% | 0.3 | 145 ft |
| DeSoto County | 12,500 | 6% | 2.5% | 0.4 | 145 ft |
| Hancock County | 11,600 | 23% | 2.2% | 0.0 | 170 ft |
| Simpson County | 11,400 | 44% | 2.8% | 0.1 | 170 ft |
| Lee County | 10,100 | 12% | 1.0% | 0.0 | 320 ft |
| Lowndes County | 9,600 | 16% | 1.5% | 0.0 | 202 ft |
| Stone County | 9,100 | 51% | 4.2% | 0.3 | 105 ft |
| Madison County | 8,300 | 8% | 2.1% | 0.0 | 185 ft |
| Monroe County | 8,200 | 24% | 1.2% | 0.1 | 240 ft |
| Lauderdale County | 8,200 | 11% | 0.9% | 0.0 | 280 ft |
| Clarke County | 7,900 | 51% | 1.1% | 0.0 | 231 ft |
| Itawamba County | 7,800 | 35% | 1.3% | 0.2 | 140 ft |
| Jasper County | 7,700 | 49% | 1.2% | 0.1 | 145 ft |
| Pontotoc County | 7,500 | 24% | 1.0% | 0.0 | 225 ft |
| Alcorn County | 7,200 | 21% | 1.3% | 0.1 | 150 ft |
| Leake County | 7,200 | 35% | 1.7% | 0.2 | 105 ft |
| Chickasaw County | 6,800 | 40% | 1.2% | 0.0 | 330 ft |
| Pike County | 6,800 | 17% | 3.0% | 0.1 | 120 ft |
| Yazoo County | 6,700 | 30% | 3.8% | 0.0 | 110 ft |
| Walthall County | 6,700 | 48% | 3.0% | 0.3 | 130 ft |
| Union County | 6,500 | 23% | 1.6% | 0.1 | 300 ft |
| George County | 6,400 | 27% | 2.6% | 0.5 | 105 ft |
| Attala County | 6,400 | 37% | 2.8% | 0.1 | 125 ft |
| Perry County | 6,400 | 56% | 2.7% | 0.1 | 104 ft |
| Forrest County | 6,200 | 8% | 2.7% | 0.3 | 95 ft |
| Lafayette County | 6,100 | 10% | 1.5% | 0.2 | 160 ft |
| Oktibbeha County | 6,100 | 13% | 1.6% | 0.0 | 440 ft |
| Greene County | 6,000 | 54% | 1.6% | 0.1 | 114 ft |
| Kemper County | 6,000 | 73% | 1.0% | 0.0 | 150 ft |
| Copiah County | 6,000 | 22% | 3.8% | 0.1 | 150 ft |
| Panola County | 6,000 | 19% | 1.6% | 0.2 | 154 ft |
| Adams County | 5,500 | 19% | 2.7% | 0.1 | 180 ft |
| Jones County | 5,400 | 8% | 2.1% | 0.2 | 125 ft |
| Covington County | 5,200 | 31% | 1.9% | 0.4 | 120 ft |
| Amite County | 5,200 | 41% | 3.8% | 0.1 | 118 ft |
| Hinds County | 5,100 | 2% | 3.1% | 0.0 | 233 ft |
| Newton County | 5,000 | 25% | 1.0% | 0.1 | 210 ft |
| Marion County | 4,600 | 17% | 3.0% | 0.4 | 125 ft |
| Holmes County | 4,500 | 29% | 2.7% | 0.1 | 135 ft |
| Bolivar County | 4,500 | 14% | 2.7% | 0.0 | 44 ft |
| Choctaw County | 4,300 | 56% | 1.8% | 0.0 | 154 ft |
| Franklin County | 4,200 | 56% | 3.9% | 0.0 | 144 ft |
| Scott County | 4,000 | 16% | 1.1% | 0.0 | 256 ft |
| Smith County | 3,900 | 29% | 1.5% | 0.3 | 125 ft |
| Tallahatchie County | 3,800 | 38% | 3.2% | 0.1 | 162 ft |
| Winston County | 3,700 | 23% | 2.6% | 0.1 | 135 ft |
| Warren County | 3,600 | 8% | 5.4% | 0.1 | 133 ft |
| Tippah County | 3,600 | 17% | 1.6% | 0.1 | 210 ft |
| Benton County | 3,500 | 44% | 1.6% | 0.1 | 145 ft |
| Clay County | 3,400 | 19% | 1.1% | 0.0 | 340 ft |
| Lamar County | 3,100 | 4% | 3.2% | 0.5 | 86 ft |
| Sunflower County | 3,100 | 15% | 1.9% | 0.0 | 100 ft |
| Tishomingo County | 2,800 | 13% | 1.5% | 0.3 | 120 ft |
| Calhoun County | 2,800 | 23% | 1.2% | 0.0 | 180 ft |
| Grenada County | 2,700 | 13% | 3.4% | 0.0 | 260 ft |
| Yalobusha County | 2,700 | 23% | 2.6% | 0.1 | 120 ft |
| Montgomery County | 2,600 | 30% | 1.4% | 0.0 | 189 ft |
| Claiborne County | 2,500 | 29% | 5.5% | 0.1 | 160 ft |
| Washington County | 2,400 | 5% | 3.4% | 0.0 | 420 ft |
| Prentiss County | 2,100 | 9% | 1.1% | 0.1 | 200 ft |
| Lawrence County | 2,000 | 17% | 3.1% | 0.1 | 128 ft |
| Webster County | 2,000 | 21% | 1.7% | 0.0 | 176 ft |
| Leflore County | 2,000 | 8% | 1.9% | 0.0 | 297 ft |
| Coahoma County | 1,900 | 9% | 1.9% | 0.0 | 100 ft |
| Noxubee County | 1,900 | 18% | 1.1% | 0.0 | 300 ft |
| Wayne County | 1,800 | 8% | 2.2% | 0.2 | 101 ft |
| Carroll County | 1,700 | 17% | 3.7% | 0.0 | 221 ft |
| Humphreys County | 1,600 | 23% | 2.3% | 0.0 | 74 ft |
| Jefferson County | 1,300 | 22% | 3.9% | 0.1 | 162 ft |
| Wilkinson County | 1,200 | 19% | 4.3% | 0.1 | 155 ft |
| Quitman County | 810 | 15% | 1.8% | 0.0 | 50 ft |
| Neshoba County | 790 | 2% | 1.3% | 0.2 | 120 ft |
| Sharkey County | 490 | 14% | 3.0% | 0.0 | 94 ft |
| Jefferson Davis County | 410 | 4% | 2.5% | 0.3 | 130 ft |
| Tunica County | 230 | 3% | 2.2% | 0.0 | 80 ft |
| Issaquena County | 90 | 10% | 2.8% | 0.0 | 92 ft |
Shading: red is among the highest counties nationally, amber the middle, green the lower range. Click a column to sort.
Most well users above the arsenic limit
- Jackson County: about 310 people
- Harrison County: about 280 people
- Marshall County: about 210 people
- Washington County: about 150 people
- Tate County: about 150 people
Test first, then treat what the test finds
We may earn a commission from links below, at no cost to you. Picks follow the testing order, not who pays. How we make money.
1. Certified lab well test
Start here, every year
A mail-in kit analyzed by a certified lab measures bacteria, nitrate, arsenic, metals and more. Test strips cannot measure arsenic or uranium reliably.
2. Sediment pre-filter
Sand, silt or cloudy water
A 5-micron cartridge after the pressure tank catches sand, silt and rust before they reach fixtures or other filters. Cartridges are cheap and swap every few months.
3. Iron and sulfur filter
Orange stains or rotten-egg smell
Air-injection or oxidizing-media filters remove orange staining and rotten-egg smell. Size one from a lab result for iron, manganese and hydrogen sulfide.
4. UV disinfection system
Coliform bacteria in a test
Inactivates bacteria and viruses; usually for private wells or after boil notices.
5. Under-sink reverse osmosis
Arsenic, nitrate or uranium in a test
The most thorough option for drinking water: PFAS, lead, nitrate, arsenic and more. Look for NSF/ANSI 58.
6. Whole-house well filter
Several problems at once
Multi-stage sediment and carbon for every tap. Add UV if bacteria shows up, and choose stages from your lab results, not a guess.
Questions
Which Mississippi counties rely most on wells?+
By share of homes: Kemper County (73%), Marshall County (62%), Perry County (56%), Choctaw County (56%), Franklin County (56%). By number of people: Jackson County (33,100), Harrison County (24,500), Pearl River County (23,700).
Is arsenic a problem in Mississippi wells?+
USGS estimates about 2,800 Mississippi well users have water above the 10 microgram per liter arsenic limit that applies to public systems, the largest numbers in Jackson County, Harrison County, Marshall County. Arsenic has no taste or smell, so only a lab test finds it.
Do I have to test my well when I sell a house in Mississippi?+
We could not confirm a statewide rule for Mississippi. Check with your county health department. Buyers can still make a lab test a condition of the offer.
How often should I test my well?+
No federal law covers private wells. EPA's drinking water limits apply to public water systems, so testing and treating a private well is up to the owner. EPA and CDC recommend testing at least once a year for coliform bacteria, nitrate, pH and total dissolved solids, and testing for arsenic, uranium, radon and other local concerns based on where you live.
Well-user counts, arsenic and nitrate figures are each a modeled estimate built from national datasets, not a count of tested wells, and well depths summarize drilling records rather than every well. Your own well can be very different from the county average, which is why the only answer for your home is a lab test. Sources: EPA Office of Research and Development, Water Source 2020 (private well estimates by census block); CDC Environmental Public Health Tracking, Well Water Index (from USGS nitrate and arsenic models); USGS, county-level domestic well population with arsenic above 10 micrograms per liter (Ayotte and others, 2017); USGS Synthesized Domestic Well Database for the Conterminous United States (SynDWell-US), McCarthy and others, 2025 (depth, where a county has 30+ usable records).