Well water in Allen Parish, Louisiana
In Allen Parish, 42% of 31 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).
31 individual samples from 15 wells, 1967 to 2020. Data refreshed September 9, 2026.
These are LDEQ monitoring wells sampled by aquifer on a rotation, so the shares describe the aquifer, not a survey of homeowners' wells.
What individual samples found
Each row summarizes every public sample for that contaminant inside Allen 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 | Samples | Detected | Above limit | Median | Highest | Limit | |
|---|---|---|---|---|---|---|---|
| Arsenic 1982 to 2020 | 31 | 77% | 42% | 2.5 | 1,112 | 10 ug/L EPA limit | |
| Lead 1982 to 2020 | 27 | 70% | 33% | 0.237 | 1,015 | 15 ug/L EPA limit | |
| Radium (226 + 228) 1983 to 2020 | 20 | 85% | 0% | 0.155 | 0.9 | 5 pCi/L EPA limit | |
| Uranium 1983 to 2020 | 18 | 44% | 0% | 0 | 1.1 | 30 ug/L EPA limit | |
| Copper 2000 to 2019 | 15 | 87% | 0% | 0.309 | 1.02 | 1.3 mg/L EPA limit | |
| Iron 2002 to 2019 | 14 | 100% | no limit | 1,200 | 105,000 | 300 ug/L nuisance level | |
| Manganese 2010 to 2019 | 13 | 100% | no limit | 990 | 3,020 | 300 ug/L health guideline |
Sampled fewer than 10 times, too few to summarize: Nitrate (5), PFOA (4), PFOS (4), Fluoride (1), Radon (8).
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What this means
The contaminants most often above their limit here are arsenic (42% of 31 samples) and lead (33% of 27 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.
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 Allen Parish
- Arsenic42% of 31 local samples were above the limit.
- Lead33% of 27 local samples were above the limit.
- Coliform bacteriaRecommended for every private well, every year.
- RadonMedian local reading is 260 pCi/L.
- FluorideDetected in 100% of local samples.
- IronDetected in 100% of local samples.
- ManganeseDetected in 100% of local samples.
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
- Copper
- Neutralizing filter to raise pH; Point-of-use reverse osmosis
- Fluoride
- Point-of-use reverse osmosis; Activated alumina; Distillation
- Iron
- Oxidizing filter whole-house; Water softener (low levels); Aeration plus filtration
Get your Allen Parish water tested at home
A licensed local water treatment company tests your tap water in your home, walks you through the numbers, and quotes treatment only if something needs fixing. Free, about 30 minutes, no obligation. Tell us what you need and we match you with a company that serves Allen Parish.
Common questions
Is there arsenic in well water in Allen Parish?
Arsenic was detected in 77% of 31 public well samples in Allen Parish, and 42% 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 Allen Parish?
The median radon level across 8 public samples in Allen Parish was 260 pCi/L, with a high of 350 pCi/L. New Hampshire recommends treatment above 2,000 pCi/L.
How often should I test a private well in Allen 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.
Sources
- USGS Water Quality Portal: 99 samples in Allen 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): 61 samples in Allen 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.
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.