Arsenic in Drinking Water in Indiana
What residents of Indiana 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, Indiana Department of Environmental Management, USGS · Last reviewed: 2025-01-01
Quick Answer
Is arsenic in drinking water a concern in Indiana?
Yes. Indiana has documented arsenic in glacial aquifer systems, particularly in the glacial outwash and buried valley aquifers of central and northern Indiana. Several Indiana counties have documented elevated arsenic in private well water from glacial sediment geology. Indiana has a significant private well population — approximately 1.2 million residents — and arsenic is one of the priority concerns for well owners.
Where does arsenic come from in Indiana's water?
Glacial outwash and buried valley aquifer geology is the primary arsenic pathway in Indiana. Reducing geochemical conditions in fine-grained glacial sediments can mobilize naturally occurring arsenic. The Teays-Mahomet buried valley aquifer system and glacial outwash deposits across northern and central Indiana have documented arsenic occurrence. Private wells and small water systems drawing from these aquifers face elevated risk.
What should Indiana residents know?
Indiana IDEM has documented arsenic occurrence in private wells across multiple northern and central Indiana counties. The state recommends private well testing for arsenic and provides guidance. Private well owners in counties with glacial outwash aquifers — particularly in the Kankakee River plain, Wabash River valley, and other glacial terrains — should test.
Key Facts
| EPA MCL | 10 µg/L (10 ppb) |
| MCLG | Zero |
| Primary source | Glacial outwash and buried valley aquifer sediments — reducing conditions mobilize natural arsenic |
| Key aquifer | Teays-Mahomet buried valley system and glacial outwash deposits across northern/central Indiana |
| State regulator | Indiana Department of Environmental Management (IDEM) |
| Private well concern | ~1.2 million Indiana residents on private wells — arsenic testing strongly recommended |
| Health effects | Bladder, lung, skin cancer; cardiovascular; diabetes risk |
| Effective treatment | Reverse osmosis (NSF/ANSI 58) or activated alumina |
Why Arsenic Matters in Indiana
Indiana's flat glaciated landscape — shaped by repeated glacial advances — left thick deposits of glacial sediment that now serve as the primary groundwater source for much of the state's rural population. These glacial sediments can contain arsenic in mineral form that mobilizes under reducing aquifer conditions. Indiana IDEM has conducted surveys of arsenic in private well water and found elevated concentrations in multiple counties. The state's 1.2 million private well users face no regulatory arsenic protection and must test and treat independently.
Indiana Arsenic Program
Indiana IDEM monitors arsenic under federal SDWIS. Indiana's glacial geology produces moderate arsenic in some aquifers, particularly in the northern part of the state. Private well owners should test for arsenic as part of a comprehensive well water test.
Indiana Utilities With Arsenic Violation Records
The utilities listed below have at least one arsenic violation on record in EPA's SDWIS database. Violations may be open or resolved — see individual utility pages for current status and risk level.
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
Private well owners across northern and central Indiana — particularly in LaPorte, Porter, Lake, Kosciusko, Fulton, Cass, and Tippecanoe counties with glacial outwash or buried valley aquifer geology — face elevated arsenic risk. Indiana's agricultural counties with high private well density are the highest priority for 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 Indiana
- 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 Indiana Department of Environmental Management-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 Indiana, 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
Indiana State Overview
All utilities and water quality data
Indiana 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.
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Indiana Department of Environmental Management ↗