Well water in Lafayette Parish, Louisiana
In Lafayette Parish, 4% of 112 tested well samples 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).
The strongest signal is PFOS: 8% of 26 local samples were above the limit, too few samples to carry the headline but first on the test list below.
1,999 test results across 14 contaminants from at least 159 wells, 1937 to 2025; chloride has the most at 364. 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, 8% of 26 PFOS results in Lafayette Parish were above the EPA limit of 4 ng/L. In that targeted sampling, 0% of 26 PFOA results in Lafayette Parish were above the EPA limit of 4 ng/L.
An estimated 33,218 people in Lafayette Parish get their drinking water from a private well, per USGS 2015 county water use. That is about 14% of residents.
Separately, the USGS national arsenic model estimates that 1% of the 33,218 people on private wells in Lafayette Parish 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 Lafayette Parish. 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 |
|---|---|---|---|---|---|---|
| PFOS 2020 to 2021 | 26 | 19% | 0 | 41 | 4 ng/L EPA limit | |
| Arsenic 1982 to 2021 | 112 | 100% | 1.4 | 26.9 | 10 ug/L EPA limit | |
| Nitrate 1937 to 2021 | 323 | 69% | 0.089 | 96.2 | 10 mg/L EPA limit | |
| Fluoride 1937 to 2021 | 180 | 99% | 0.24 | 2 | 4 mg/L EPA limit | |
| Copper 1982 to 2021 | 112 | 71% | 0.001 | 0.286 | 1.3 mg/L EPA limit | |
| Lead 1982 to 2021 | 112 | 54% | 0.018 | 0.918 | 15 ug/L EPA limit | |
| Uranium 2000 to 2021 | 108 | 72% | 0.043 | 3.17 | 30 ug/L EPA limit | |
| PFOA 2020 to 2021 | 26 | 8% | 0 | 3.7 | 4 ng/L EPA limit | |
| Chloride 1937 to 2025 | no limit | 364 | 100% | 9.46 | 1,900 | 250 mg/L nuisance level |
| Iron 1942 to 2021 | no limit | 225 | 88% | 419 | 65,000 | 300 ug/L nuisance level |
| Manganese 1949 to 2021 | no limit | 197 | 97% | 164 | 5,300 | 300 ug/L health guideline |
| Sodium 1942 to 2021 | no limit | 185 | 100% | 20.9 | 830 | 20 mg/L health guideline |
| Radon 2000 to 2013 | no limit | 23 | 100% | 380 | 2,220 | 2,000 pCi/L health guideline |
Sampled fewer than 10 times, too few to summarize: Radium (226 + 228) (6).
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%107 samples | 3%104 samples | 2%60 samples | 0%52 samples |
| Fluoride | 0%72 samples | 0%52 samples | 0%30 samples | 0%26 samples |
| Arsenic | n/a | 0%52 samples | 7%30 samples | 8%26 samples |
| Copper | n/a | 0%52 samples | 0%30 samples | 0%26 samples |
| Lead | n/a | 0%52 samples | 0%30 samples | 0%26 samples |
| Uranium | n/a | 0%52 samples | 0%30 samples | 0%26 samples |
Nitrate, fluoride, arsenic, copper, lead, uranium have held within a few points between the two most recent periods with enough samples.
Closer than the county
See the sampled wells near your address
The same records, drawn around one point: which wells within a few miles were sampled and what they found, how deep the wells next to you were drilled, and any leaking tank or cleanup site within a mile.
Check my addressWhat this means
The contaminants most often above their limit here are pfos (8% of 26 samples), arsenic (4% of 112 samples), and nitrate (2% of 323 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 Lafayette Parish
- 1PFOS8% of 26 local samples were above the limit.
- 2Arsenic4% of 112 local samples were above the limit.
- 3Nitrate2% of 323 local samples were above the limit.
- 4Coliform bacteriaRecommended for every private well, every year.
- 5RadonMedian local reading is 380 pCi/L.
- 6ChlorideDetected in 100% of local samples.
- 7FluorideDetected in 99% of local samples.
Test your Lafayette Parish well for PFOS, arsenic and nitrate
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 $209Already 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 Lafayette Parish numbers, $29. Every line explained, ranked by what matters, with the fix for each.
The rock under Lafayette Parish
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 parish 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
PFOS
Granular activated carbon whole-house; Point-of-use reverse osmosis; Anion exchange
Arsenic
Point-of-use reverse osmosis; Adsorptive media (iron-based) whole-house; Anion exchange
Nitrate
Point-of-use reverse osmosis; Anion exchange; Distillation
Iron
Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
Manganese
Oxidizing filter (greensand, birm) whole-house; Water softener (low levels); Point-of-use reverse osmosis
Systems we would look at first
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For PFOS
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
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 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 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 iron
Iron and manganese oxidizing filter
whole-house, at the point of entry, about $1,800
Air-injection or greensand media; fixes staining at the source.
Free, no obligation
Get on the list for a free in-home water test in Lafayette Parish
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Common questions
Is there arsenic in well water in Lafayette Parish?
Arsenic was detected in 100% of 112 public well samples in Lafayette Parish, and 4% 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 Lafayette Parish?
The median radon level across 23 public samples in Lafayette Parish was 380 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 Lafayette Parish?
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 near Lafayette Parish
Closest first. Groundwater does not stop at a line on a map, so the next parish over is a fair second opinion.
Want the numbers themselves? Download the Louisiana dataset as CSV, every county and town, with the sources named.
Sources
- USGS Water Quality Portal: 1,981 samples in Lafayette Parish. 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): 18 samples in Lafayette Parish. 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 33,218 people on private wells in Lafayette Parish 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.