Arsenic in Drinking Water in Ohio
What residents of Ohio 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, Ohio EPA, USGS · Last reviewed: 2025-01-01
Quick Answer
Is arsenic in drinking water a concern in Ohio?
Arsenic is a moderate concern in Ohio, primarily from glacial aquifer geology in the western and northern parts of the state and from coal mining legacy in eastern Ohio's Appalachian coalfields. Ohio's glaciated terrain contains mineral sediments that can release arsenic under reducing groundwater conditions. Eastern Ohio's coal mining history has added arsenic through pyrite oxidation similar to West Virginia and Kentucky.
Where does arsenic come from in Ohio's water?
Two primary pathways: glacial outwash and alluvial aquifer geology in western and northern Ohio (naturally occurring arsenic from mineral sediments under reducing conditions), and coal mine drainage in eastern Ohio's Appalachian foothill counties (arsenic released from pyrite in coal seams). Private well owners relying on shallow aquifers in these regions face the most direct risk.
What should Ohio residents know?
Ohio EPA monitors public water systems for arsenic compliance. Private well owners in western Ohio counties with glacial outwash aquifers and eastern Ohio counties in the Appalachian coalfield zone should test for arsenic. Ohio has approximately 1 million residents relying on private wells — unregulated for arsenic.
Key Facts
| EPA MCL | 10 µg/L (10 ppb) |
| MCLG | Zero |
| Primary source | Glacial aquifer sediments (western OH); coal mine drainage from pyrite (eastern OH Appalachian counties) |
| State regulator | Ohio EPA |
| Health effects | Bladder, lung, skin cancer; cardiovascular; diabetes risk |
| Effective treatment | Reverse osmosis or activated alumina; iron/manganese oxidation filters useful for iron-rich mine drainage |
Why Arsenic Matters in Ohio
Ohio's arsenic concerns span the state geographically. Western Ohio's glaciated terrain and alluvial river valley aquifers can mobilize naturally occurring arsenic under reducing conditions. Eastern Ohio's coal country — particularly Muskingum, Guernsey, Morgan, Perry, Hocking, and Vinton counties — has documented arsenic from coal mine drainage similar to neighboring West Virginia and Kentucky. Ohio EPA has documented multiple cases of arsenic exceedance in small public water systems and provides guidance for private well owners.
Ohio Arsenic Program
Ohio EPA monitors arsenic under federal SDWIS. Ohio's glacial geology in the northern part of the state has documented moderate arsenic in some aquifers. The Appalachian region in southeastern Ohio has arsenic associated with coal and sulfide geology. Private well owners in both regions should test for arsenic.
Largest Ohio Water Utilities
No arsenic violations on record in EPA SDWIS for Ohio 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
Private well owners in western Ohio counties with glacial outwash aquifers (Auglaize, Mercer, Darke, Shelby, Van Wert) and eastern Ohio Appalachian coalfield counties (Muskingum, Guernsey, Morgan, Perry, Hocking, Vinton, Meigs) face the most relevant arsenic risk.
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 Ohio
- 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 Ohio EPA-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 Ohio, 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
Ohio State Overview
All utilities and water quality data
Ohio 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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