Arsenic in Drinking Water in Pennsylvania
What residents of Pennsylvania 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, Pennsylvania Department of Environmental Protection, USGS · Last reviewed: 2025-01-01
Quick Answer
Is arsenic in drinking water a concern in Pennsylvania?
Yes. Pennsylvania has significant arsenic concerns for private well users, particularly in the Piedmont and Blue Ridge regions of southeastern and south-central Pennsylvania where crystalline bedrock geology creates conditions for arsenic occurrence. Pennsylvania also has arsenic from coal mining drainage in the Anthracite and Bituminous coal regions. Approximately 25% of Pennsylvania residents use private wells.
Where does arsenic come from in Pennsylvania's water?
Three primary pathways exist in Pennsylvania: (1) Crystalline bedrock geology in the Piedmont (Chester, Lancaster, Berks, and York counties), (2) Anthracite coal mining drainage in Schuylkill, Carbon, Northumberland, Columbia, and Luzerne counties, and (3) Bituminous coal mining in the southwestern coalfields (Allegheny, Westmoreland, Washington, Greene, Fayette counties). Private wells in all three regions face elevated risk.
What should Pennsylvania residents know?
Pennsylvania private well owners should test for arsenic regardless of county. Pennsylvania DEP requires arsenic testing at real estate transfer for properties with private wells — an important consumer protection. The state provides a list of certified laboratories and guidance on treatment. Standard pitcher filters do not remove arsenic.
Key Facts
| EPA MCL | 10 µg/L (10 ppb) |
| MCLG | Zero |
| Primary source | Piedmont crystalline bedrock (SE PA); Anthracite coal mine drainage (NE PA); Bituminous coal drainage (SW PA) |
| State requirement | Arsenic testing required at real estate transfer for private well properties |
| Private well concern | ~25% of PA residents on private wells — arsenic a priority contaminant statewide |
| State regulator | Pennsylvania Department of Environmental Protection (PA DEP) |
| Health effects | Bladder, lung, skin cancer; cardiovascular; diabetes risk |
| Effective treatment | Reverse osmosis or activated alumina; iron oxidation filters for coal mine drainage water |
Why Arsenic Matters in Pennsylvania
Pennsylvania's arsenic picture is complex due to its diverse geology. Southeastern Pennsylvania's Piedmont crystalline bedrock creates arsenic exposure similar to neighboring Maryland, Delaware, and New Jersey. The state's extensive coal mining legacy — in both the Anthracite region of the northeast and the Bituminous fields of the southwest — adds acid mine drainage as a secondary pathway. Pennsylvania DEP has documented arsenic as one of the most frequently detected contaminants in private well surveys and has prioritized consumer education. The state's 25% private well rate means about 3 million Pennsylvanians may face unregulated arsenic exposure.
Pennsylvania Arsenic Program
Pennsylvania DEP monitors arsenic under federal SDWIS and has documented arsenic in private wells in the Piedmont crystalline rock counties of southeastern Pennsylvania (Chester, Lancaster, York) and in the Reading Prong — a high-arsenic geologic zone. Pennsylvania's Private Well Testing Act requires arsenic testing at real estate transfer. DEP has detailed county-level arsenic occurrence maps available to homeowners.
Pennsylvania 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.
Aqua Pa Main System
Pennsylvania · 822,600 served
Hampton Shaler Water Authority
Pennsylvania · 61,949 served
Southwestern Pa Water Auth
Pennsylvania · 40,200 served
Northampton Bucks Co Mun Auth
Pennsylvania · 36,750 served
Guilford Water Auth
Pennsylvania · 28,135 served
Horsham Water&sewer Authority
Pennsylvania · 26,000 served
Muhlenberg Twp Muni Auth
Pennsylvania · 21,000 served
Center Twp Water Auth
Pennsylvania · 19,000 served
Slippery Rock Muni Auth
Pennsylvania · 15,778 served
Mun Water Auth of Aliquippa
Pennsylvania · 15,685 served
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 southeastern Piedmont counties (Chester, Lancaster, Berks, York, Adams), Anthracite coal region counties (Schuylkill, Carbon, Northumberland, Luzerne), and southwestern coalfield counties (Allegheny, Westmoreland, Washington, Greene, Fayette) 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 Pennsylvania
- 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 Pennsylvania Department of Environmental Protection-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 Pennsylvania, 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
Pennsylvania State Overview
All utilities and water quality data
Pennsylvania 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
Pennsylvania Department of Environmental Protection ↗