Private wells
Louisiana well water: who's on a well and what to test for
People on private wells
873,300
Homes on wells
18.6%
Est. above arsenic limit
6,500
Every Louisiana 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.
| St. Tammany Parish | 86,200 | 33% | 1.4% | 0.0 | 200 ft |
| Tangipahoa Parish | 52,000 | 39% | 1.4% | 0.1 | 120 ft |
| Livingston Parish | 41,300 | 30% | 1.7% | 0.0 | 270 ft |
| Lafayette Parish | 41,100 | 16% | 1.8% | 0.1 | 118 ft |
| Calcasieu Parish | 39,200 | 17% | 1.2% | 0.0 | 235 ft |
| Ascension Parish | 38,000 | 31% | 1.6% | 0.0 | 420 ft |
| Caddo Parish | 32,800 | 14% | 2.0% | 0.1 | 200 ft |
| Vermilion Parish | 27,500 | 47% | 2.5% | 0.0 | 125 ft |
| Bossier Parish | 24,600 | 19% | 1.9% | 0.0 | 195 ft |
| St. Landry Parish | 23,800 | 28% | 2.1% | 0.0 | 150 ft |
| Washington Parish | 23,600 | 51% | 2.5% | 0.3 | 110 ft |
| Rapides Parish | 22,900 | 17% | 1.9% | 0.1 | 120 ft |
| Ouachita Parish | 21,700 | 12% | 1.6% | 0.1 | 70 ft |
| Acadia Parish | 21,200 | 34% | 2.8% | 0.0 | 170 ft |
| Vernon Parish | 20,500 | 42% | 0.9% | 0.1 | 120 ft |
| Iberia Parish | 20,500 | 29% | 1.9% | 0.0 | 220 ft |
| Lafourche Parish | 18,500 | 19% | 4.2% | 0.0 | 220 ft |
| Beauregard Parish | 18,200 | 48% | 1.0% | 0.1 | 120 ft |
| St. Martin Parish | 16,000 | 32% | 1.5% | 0.0 | 150 ft |
| Avoyelles Parish | 14,200 | 34% | 1.8% | 0.1 | 127 ft |
| East Baton Rouge Parish | 13,300 | 3% | 1.8% | 0.0 | 265 ft |
| Sabine Parish | 12,900 | 60% | 1.3% | 0.0 | 175 ft |
| De Soto Parish | 12,200 | 47% | 1.7% | 0.1 | 210 ft |
| Union Parish | 11,600 | 56% | 1.5% | 0.1 | 82 ft |
| Webster Parish | 11,400 | 31% | 1.3% | 0.1 | 205 ft |
| Jefferson Davis Parish | 11,200 | 34% | 1.4% | 0.0 | 160 ft |
| Franklin Parish | 10,900 | 55% | 2.0% | 0.4 | 45 ft |
| Evangeline Parish | 10,100 | 30% | 1.4% | 0.0 | 145 ft |
| Natchitoches Parish | 9,900 | 29% | 1.2% | 0.2 | 132 ft |
| Grant Parish | 9,800 | 51% | 2.8% | 0.5 | 70 ft |
| Lincoln Parish | 9,700 | 21% | 1.1% | 0.1 | 340 ft |
| Richland Parish | 9,400 | 49% | 1.9% | 0.5 | 45 ft |
| East Feliciana Parish | 8,800 | 49% | 2.9% | 0.1 | 125 ft |
| Allen Parish | 8,200 | 40% | 1.0% | 0.1 | 100 ft |
| St. Helena Parish | 8,100 | 75% | 1.9% | 0.1 | 120 ft |
| Terrebonne Parish | 8,000 | 8% | 2.6% | 0.0 | n/a |
| Claiborne Parish | 7,500 | 48% | 1.0% | 0.0 | 267 ft |
| Morehouse Parish | 7,200 | 27% | 1.6% | 0.1 | 89 ft |
| Jackson Parish | 6,300 | 43% | 1.4% | 0.1 | 120 ft |
| Bienville Parish | 6,300 | 51% | 1.2% | 0.1 | 155 ft |
| Pointe Coupee Parish | 6,300 | 29% | 4.7% | 0.0 | 160 ft |
| Winn Parish | 6,100 | 47% | 2.1% | 0.0 | 155 ft |
| Iberville Parish | 6,000 | 21% | 2.0% | 0.0 | 180 ft |
| West Carroll Parish | 5,700 | 58% | 2.1% | 0.1 | 56 ft |
| Catahoula Parish | 5,400 | 61% | 2.2% | 0.0 | 108 ft |
| Caldwell Parish | 5,100 | 58% | 2.1% | 0.1 | 100 ft |
| La Salle Parish | 5,000 | 37% | 2.9% | 0.2 | 90 ft |
| Red River Parish | 4,700 | 66% | 1.4% | 0.2 | 80 ft |
| West Feliciana Parish | 4,200 | 39% | 3.6% | 0.1 | 172 ft |
| Concordia Parish | 3,500 | 19% | 1.6% | 0.0 | 101 ft |
| Assumption Parish | 3,000 | 15% | 1.7% | 0.0 | 190 ft |
| West Baton Rouge Parish | 3,000 | 11% | 2.8% | 0.0 | 170 ft |
| Cameron Parish | 3,000 | 54% | 2.3% | 0.0 | 198 ft |
| St. Mary Parish | 2,900 | 6% | 2.0% | 0.0 | 260 ft |
| St. Charles Parish | 2,500 | 5% | 1.8% | 0.0 | n/a |
| Jefferson Parish | 2,400 | 1% | 2.4% | 0.0 | n/a |
| Madison Parish | 1,800 | 20% | 3.6% | 0.0 | 70 ft |
| Tensas Parish | 1,400 | 29% | 2.2% | 0.0 | 93 ft |
| East Carroll Parish | 1,400 | 25% | 3.2% | 0.0 | 118 ft |
| Plaquemines Parish | 1,000 | 6% | 2.4% | 0.0 | n/a |
| St. John the Baptist Parish | 770 | 2% | 1.8% | 0.0 | 320 ft |
| St. James Parish | 600 | 3% | 3.0% | 0.0 | 284 ft |
| St. Bernard Parish | 520 | 2% | 1.9% | 0.0 | n/a |
| Orleans Parish | 290 | 0% | 1.8% | 0.0 | 430 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
- St. Tammany Parish: about 1,100 people
- Ascension Parish: about 610 people
- Tangipahoa Parish: about 550 people
- Vermilion Parish: about 430 people
- Livingston Parish: about 410 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.
Mail-in certified lab well water test
Mid-range2. 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.
5-micron whole-house sediment filter
Budget3. 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.
Air-injection iron and sulfur filter
Premium4. UV disinfection system
Coliform bacteria in a test
Inactivates bacteria and viruses; usually for private wells or after boil notices.
12 GPM whole-house UV purifier
Premium5. 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.
Waterdrop G3P600 tankless RO
Price at Waterdrop, checked Oct 5, 2026or compare on Amazon
iSpring RCC7AK reverse osmosis
Mid-range6. 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.
Waterdrop WHF21 2-stage whole-house filter
Mid-rangeQuestions
Which Louisiana counties rely most on wells?+
By share of homes: St. Helena Parish (75%), Red River Parish (66%), Catahoula Parish (61%), Sabine Parish (60%), Caldwell Parish (58%). By number of people: St. Tammany Parish (86,200), Tangipahoa Parish (52,000), Livingston Parish (41,300).
Is arsenic a problem in Louisiana wells?+
USGS estimates about 6,500 Louisiana well users have water above the 10 microgram per liter arsenic limit that applies to public systems, the largest numbers in St. Tammany Parish, Ascension Parish, Tangipahoa Parish. 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 Louisiana?+
We could not confirm a statewide rule for Louisiana. 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).