Arsenic in Drinking Water in Louisiana
What residents of Louisiana need to know about arsenic in drinking water — including natural geological sources, private well risk, which utilities have documented violations, and how to remove arsenic from tap water.
Source: EPA SDWIS, Louisiana Department of Health, USGS · Last reviewed: 2025-01-01
Quick Answer
Is arsenic in drinking water a concern in Louisiana?
Arsenic is a moderate concern in Louisiana, primarily from the Mississippi River alluvial aquifer system and from naturally occurring arsenic in the Gulf Coastal Plain sedimentary geology. Louisiana draws most of its drinking water from surface water (Mississippi River and tributaries) or from shallow alluvial aquifers — both of which can have naturally occurring arsenic from sediment chemistry.
Where does arsenic come from in Louisiana's water?
Naturally occurring arsenic in Louisiana's Gulf Coastal Plain sedimentary aquifers and Mississippi River alluvial deposits is the primary pathway. Reducing geochemical conditions in Louisiana's shallow aquifers — common in the wet, organic-rich soils of coastal Louisiana — can mobilize arsenic from sediments. Private wells and small water systems drawing from shallow aquifers face the highest risk.
What should Louisiana residents know?
Rural Louisiana private well owners drawing from shallow Gulf Coastal Plain or alluvial aquifers should test for arsenic. Louisiana LDH monitors public water systems, but private wells — primarily in rural parishes — are unregulated. The state's petrochemical industrial corridor may also contribute arsenic from industrial sources in some areas.
Key Facts
| EPA MCL | 10 µg/L (10 ppb) |
| MCLG | Zero |
| Primary source | Gulf Coastal Plain sedimentary aquifer geology; Mississippi alluvial deposits with reducing geochemical conditions |
| State regulator | Louisiana Department of Health |
| Health effects | Bladder, lung, skin cancer; cardiovascular; diabetes |
| Effective treatment | Reverse osmosis (NSF/ANSI 58) or activated alumina |
Why Arsenic Matters in Louisiana
Louisiana's flat coastal geology and high water table create conditions where reducing geochemical processes mobilize arsenic from sediments into shallow groundwater. The Mississippi River Delta region, with its thick accumulations of organic-rich alluvial sediments, is particularly susceptible to this process. Louisiana's public water systems drawing from the Mississippi River or deeper aquifers generally maintain compliance, but rural private well users in shallow aquifer areas face more direct risk.
Louisiana Arsenic Program
Louisiana DHH monitors arsenic under federal SDWIS. Louisiana's Coastal Plain geology generally produces lower natural arsenic compared to hard-rock states, though the Mississippi Alluvial aquifer has localized elevated arsenic in some areas. Arsenic is a lower-priority concern for most Louisiana residents.
Largest Louisiana Water Utilities
No arsenic violations on record in EPA SDWIS for Louisiana utilities in our database. Browse the largest utilities to review their full water quality record.
How Does Arsenic Get Into Drinking Water?
Arsenic in drinking water is almost always naturally occurring — it leaches from arsenic-bearing rocks and minerals into groundwater over time. New England granite, Southwest volcanic geology, and Upper Midwest glacial aquifers are the primary high-risk formations. It has no taste, odor, or color.
Full arsenic overview — geology maps, health effects, all 50 statesWho Should Pay Closest Attention
Rural private well owners in Louisiana's coastal parishes and alluvial lowlands, particularly in the Mississippi River Delta region and in parishes with shallow aquifer dependence, should prioritize arsenic testing.
Private well owners near mining districts or agricultural areas
Residents in states with documented volcanic or geothermal geology
Long-term consumers of water from small groundwater systems
Households in homes built before 1960 with older well casings
Residents whose well water has never been tested for arsenic
Anyone living in a state where bedrock wells are common
How to Check Your Situation in Louisiana
- 1
Identify your water source. If you use a public utility, use the ZIP lookup on this page to find your system and check its compliance record.
- 2
If on public water, review your utility's most recent Consumer Confidence Report (CCR) for arsenic monitoring data. The MCL is 10 ppb — your report should show recent test results.
- 3
If on a private well, order an arsenic test from a Louisiana Department of Health-certified laboratory. A basic arsenic test costs $15–$40. The state agency website maintains a certified lab list.
- 4
Test your well at the tap — not just at the wellhead. The entire water distribution system within your home can affect water quality.
- 5
If your test shows arsenic above 5 ppb, install certified treatment immediately. If above 10 ppb, do not use the water for drinking or cooking until treatment is installed.
- 6
Retest after installing treatment to confirm it is working as certified. Replace filter media on the manufacturer's schedule — an exhausted filter may not perform as rated.
Treatment Options for Arsenic
Boiling does not remove arsenic — it concentrates it. Standard activated carbon filters (Brita, etc.) do not effectively remove arsenic. Certified treatment is required.
NSF/ANSI Standard 58 — Reverse Osmosis
RO systems certified to NSF/ANSI 58 remove 85–95% of arsenic. Under-sink installation. Most effective for removing multiple contaminants simultaneously. Replace membranes and pre-filters on schedule.
Activated Alumina Filters
Activated alumina is specifically designed for arsenic and fluoride removal. Point-of-use or whole-house options available. Must be certified by NSF International or WQA for arsenic reduction. Requires periodic media regeneration or replacement.
Iron/Manganese Oxidation Filters
Effective for arsenic in iron-rich well water, which is common in the Midwest and New England. Oxidation converts dissolved iron and arsenic to a form that can be filtered out. Best when arsenic is co-occurring with high iron levels.
What does NOT work for arsenic
Standard activated carbon filters (Brita, refrigerator filters, most pitcher filters) do NOT effectively remove arsenic. Boiling concentrates arsenic. Water softeners do not remove arsenic. Only use products with NSF certification specifically for arsenic reduction.
Take Action Now
If you use a private well in Louisiana, test for arsenic — especially if you are in a region with granite, volcanic, or sedimentary geology. A basic arsenic test costs $15–$40 at a state-certified lab.
Public water users: check your utility's Consumer Confidence Report (CCR) for arsenic results. The EPA MCL is 10 ppb — any detection warrants attention.
If arsenic is detected above 10 ppb (or even below it, given MCLG is zero), install an NSF/ANSI 58-certified reverse osmosis system for drinking and cooking water.
Standard carbon filters do NOT remove arsenic — do not rely on a Brita or refrigerator filter for arsenic protection.
Frequently Asked Questions
Related Pages
Arsenic — National Overview
All U.S. utilities with arsenic records
Louisiana State Overview
All utilities and water quality data
Louisiana Well Water Guide
Testing, risks & certified labs for private wells
Reverse Osmosis Guide
Removes 85–95% of arsenic
Best Arsenic Filter Guide
What actually works (carbon doesn't)
PFAS in Drinking Water
The 'forever chemical' contamination overview
All Contaminants
Complete reference library
Data Sources & Provenance
All data on this page is sourced from official U.S. government or public datasets.
Find Your Utility
State Regulator
Louisiana Department of Health ↗