Well water in Louisiana

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Testing strongly recommended

tested well samples in Louisiana exceeded the EPA limit for arsenic (10 ug/L), based on public data from USGS Water Quality Portal and Louisiana LDEQ ambient ground water results (LDH Private Well Initiative).

92,046 test results across 14 contaminants from at least 11,419 wells, 1910 to 2026; chloride has the most at 34,814. Data refreshed September 15, 2026.

Compiled by Nick at Well Water Nerd from public records. How these pages are built

These are LDEQ monitoring wells sampled by aquifer on a rotation, so the shares describe the aquifer, not a survey of homeowners' wells. In that targeted sampling, 4% of 52 PFOS results in Louisiana were above the EPA limit of 4 ng/L. In that targeted sampling, 0% of 52 PFOA results in Louisiana were above the EPA limit of 4 ng/L.

An estimated 491,582 people in Louisiana get their drinking water from a private well, per USGS 2015 county water use.

Separately, the USGS national arsenic model estimates that 1% of the 491,582 people on private wells in Louisiana draw water above 10 ug/L (the model's range is <1% to 2%), from geology and well depth rather than local tests.

What individual samples found

Each row summarizes every public sample for that contaminant inside Louisiana. Above limit means above the EPA maximum contaminant level; where EPA has no enforceable limit, the row shows a health guideline or nuisance level instead.

Contaminant	Above limit	Samples	Detected	Median	Highest	Limit
Arsenic 1972 to 2021	22%	1,119	68%	1	4,380	10 ug/L EPA limit
Lead 1972 to 2021	19%	1,071	63%	0	1,090	15 ug/L EPA limit
PFOS 2020 to 2021	4%	52	13%	0	41	4 ng/L EPA limit
Radium (226 + 228) 1977 to 2020	1%	282	90%	0.22	120	5 pCi/L EPA limit
Nitrate 1927 to 2021	1%	10,159	72%	0.02	260	10 mg/L EPA limit
Copper 1952 to 2021	<1%	1,146	71%	0.001	6.31	1.3 mg/L EPA limit
Fluoride 1935 to 2021	<1%	9,848	96%	0.3	15	4 mg/L EPA limit
Uranium 1977 to 2021	0%	527	57%	0.011	15.8	30 ug/L EPA limit
PFOA 2020 to 2021	0%	52	6%	0	3.7	4 ng/L EPA limit
Chloride 1910 to 2026	no limit	34,814	100%	52	130,000	250 mg/L nuisance level
Iron 1910 to 2021	no limit	13,920	98%	760	348,000	300 ug/L nuisance level
Manganese 1945 to 2021	no limit	10,297	96%	180	37,300	300 ug/L health guideline
Sodium 1910 to 2021	no limit	8,570	100%	69	85,000	20 mg/L health guideline
Radon 1996 to 2014	no limit	189	99%	260	2,220	2,000 pCi/L health guideline

Over time

Share of samples above the limit by period. A cell needs ten samples to show; a comparison needs twenty in each period. Later periods sample fewer wells, and often the ones already known to have a problem.

Contaminant	before 2000	2000s	2010s	2020s
Nitrate	1%9,089 samples	2%715 samples	<1%251 samples	0%104 samples
Fluoride	<1%8,450 samples	<1%882 samples	0%464 samples	0%52 samples
Copper	<1%485 samples	0%270 samples	<1%317 samples	9%74 samples
Arsenic	3%460 samples	12%253 samples	52%316 samples	40%90 samples
Lead	0%457 samples	10%247 samples	54%297 samples	26%70 samples
Uranium	0%130 samples	0%222 samples	0%123 samples	0%52 samples

Copper above the limit in Louisiana rose from <1% of 317 samples in the 2010s to 9% of 74 in the 2020s.

Arsenic above the limit in Louisiana fell from 52% of 316 samples in the 2010s to 40% of 90 in the 2020s.

Lead above the limit in Louisiana fell from 54% of 297 samples in the 2010s to 26% of 70 in the 2020s.

Nitrate, fluoride, uranium have held within a few points between the two most recent periods with enough samples.

What this means

The contaminants most often above their limit here are arsenic (22% of 1,119 samples), lead (19% of 1,071 samples), and pfos (4% of 52 samples). A well next door can differ sharply from yours because bedrock fractures, well depth and plumbing all matter, so these rates describe the area, not your tap.

Chloride, Iron, and Manganese are widespread in local groundwater. They are mainly a staining and taste problem, but high manganese also carries a health advisory for infants.

What to test for in Louisiana

1
Arsenic
22% of 1,119 local samples were above the limit.
2
Lead
19% of 1,071 local samples were above the limit.
3
PFOS
4% of 52 local samples were above the limit.
4
Radium (226 + 228)
1% of 282 local samples were above the limit.
5
Nitrate
1% of 10,159 local samples were above the limit.
6
Copper
<1% of 1,146 local samples were above the limit.
7
Fluoride
<1% of 9,848 local samples were above the limit.

Test your Louisiana well for arsenic, lead and PFOS

Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.

Order the Tap Score well water test kit, from $209 Already tested? Upload the report

Just want bacteria checked first? Tap Score coliform and E. coli test, $99. Coliform and E. coli are the tests every well needs every year.

Want a quick look before paying for a lab? Home well water test strips on Amazon check hardness, iron, pH and nitrate in minutes. They are a screen, not a result: arsenic, bacteria, uranium and PFAS need a certified lab.

Affiliate links: the merchant pays us a commission and the price is the same for you. It does not change what the data above says. As an Amazon Associate we earn from qualifying purchases.

Where to get a well tested in Louisiana: certified labs, state programs and prices.

Already have results back? Get your lab report read against the Louisiana numbers, $29. Every line explained, ranked by what matters, with the fix for each.

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Send me the Louisiana report

The numbers above, which tests to order and where, and the treatment that fits the local profile, in one email.

The rock under Louisiana

Coastal lowlands aquifer system

Semiconsolidated sand. Coastal plain sands like these give steady yields at moderate depth. Salt water and sodium are the usual issues near the coast, and nitrate where the water table is shallow; arsenic and radon from bedrock are less common.

Classification from the USGS Principal Aquifers of the United States (national map, 2003 edition, GIS release 2015), read at the state centroid. A single well can sit in a different unit, especially near a boundary.

Official help in Louisiana

Two places to start that are not selling anything: the state program that answers private well questions, and its list of labs certified to run drinking water tests. A certified lab is the difference between a result you can act on and a number.

Private Well Initiative, Louisiana Department of Health
Laboratory Certification, Louisiana Department of Health

Treatment that fits the local profile

Arsenic

Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange

Lead

Point-of-use reverse osmosis; Certified lead-removal carbon filter; Neutralizing filter to raise pH and stop leaching

PFOS

Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange

Radium (226 + 228)

Water softener (cation exchange); Point-of-use reverse osmosis

Nitrate

Point-of-use reverse osmosis; Anion exchange; Distillation

Systems we would look at first

Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.

For arsenic

Under-sink reverse osmosis system

under-sink or countertop, about $300

Look for NSF/ANSI 58 certification listing the contaminant you need removed.

For arsenic

Whole-house arsenic and uranium filter

whole-house, at the point of entry, about $2,500

Adsorptive iron-based media; sized to your well yield.

For arsenic

Aquasana SmartFlow reverse osmosis

under-sink or countertop, about $225

Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.

For lead

Aquasana Claryum 3-Stage under-sink filter

under-sink or countertop, about $175

Certified to NSF/ANSI 53 to reduce 99% of lead and 99.7% of PFOA and PFOS at the tap. Not a fix for arsenic, nitrate or bacteria.

For lead

Acid neutralizing filter

whole-house, at the point of entry, about $1,200

Raises pH so plumbing stops leaching lead and copper.

For PFOS

Whole-house PFAS carbon system

whole-house, at the point of entry, about $3,000

Granular activated carbon certified to NSF/ANSI 53 for PFOA and PFOS; replace media on schedule.

For PFOS

Aquasana HealthShield whole-house filter

whole-house, at the point of entry, about $2,099

Whole-house carbon system the maker certifies to reduce PFAS (PFOA and PFOS) and VOCs at every tap; a UV option adds bacteria protection.

Common questions

Is there arsenic in well water in Louisiana?

Arsenic was detected in 68% of 1,119 public well samples in Louisiana, and 22% were above the EPA limit of 10 ug/L. Arsenic has no taste or smell; a lab test is the only way to know your level.

How high is radon in well water in Louisiana?

The median radon level across 189 public samples in Louisiana was 260 pCi/L, with a high of 2,220 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.

How often should I test a private well in Louisiana?

Test for bacteria and nitrate every year. Test once for arsenic, uranium, radon, fluoride, manganese and PFAS, then again every three to five years or after any change in taste, color, or plumbing.

Parishes in Louisiana

Want the numbers themselves? Download the Louisiana dataset as CSV, every county and town, with the sources named.

Sources

USGS Water Quality Portal: 89,860 samples in Louisiana. Data from the Water Quality Portal, a service of USGS, EPA and USDA; groundwater samples collected by USGS and cooperators. Retrieved September 3, 2026.
Louisiana LDEQ ambient ground water results (LDH Private Well Initiative): 2,186 samples in Louisiana. Ground water sample results from the LDEQ Ambient Ground Water Monitoring Program, published by the Louisiana Department of Health Private Well Initiative. Retrieved September 9, 2026.
USGS national arsenic model (Ayotte 2017): estimated share of 491,582 people on private wells in Louisiana above 10 ug/L of arsenic, from geology, well depth and land use. County estimates of domestic well users with arsenic above 10 ug/L from the USGS national logistic regression model (Ayotte, Medalie and Qi, 2017), with private well population from the USGS 2015 county water-use compilation (Dieter and others, 2018). Retrieved September 15, 2026.

Non-detects count as samples and are treated as zero when computing medians. Exactly at the limit counts as not above it. A sample belongs to the town containing the well's reported coordinates.