Tested Water
Menu

Arsenic in Pennsylvania well water, by county

By the Tested Water teamLab data from the USGS and EPA Water Quality Portal, 2000 to 2023Updated November 8, 2026

Arsenic is widespread, over the limit in 15% or more of tested wells, in 1 of the 23 Pennsylvania counties with 10 or more tested wells. A county's share tells you how likely a problem is nearby. Only a test of your own well tells you what's in it.

Find an arsenic test See every county

How Pennsylvania compares with the rest of the country

Across Pennsylvania, about 1 in 24 tested wells had arsenic over the EPA limit of 10 µg/L (52 of 1,247). Across all tested wells in the US it's about 1 in 9. That's less often than in the country as a whole. Counties still differ, so check yours below.

Why it matters: Drinking it for years raises the risk of skin, bladder and lung cancer.

Arsenic dissolves out of certain rocks and old sediments, so it can be high even where nobody has polluted anything.

Arsenic in tested wells, county by county

Share of each county's tested wells with at least one result over the EPA limit of 10 µg/L. Counties need 10 or more tested wells to be listed. Widespread means 15% or more, worth checking 5 to 15%, rare under 5%.

CountyWells testedWells over the limitLevel
Montgomery County 31
23% 7 of 31
 Widespread
Berks County 39
13% 5 of 39
 Worth checking
Lycoming County 87
10% 9 of 87
 Worth checking
Tioga County 72
8% 6 of 72
 Worth checking
Dauphin County 30
7% 2 of 30
 Worth checking
Bucks County 32
6% 2 of 32
 Worth checking
Wayne County 143
4% 6 of 143
 Rare
Northumberland County 26
4% 1 of 26
 Rare
Bradford County 110
4% 4 of 110
 Rare
Susquehanna County 28
4% 1 of 28
 Rare
Potter County 58
3% 2 of 58
 Rare
Clinton County 59
2% 1 of 59
 Rare
Pike County 110
1% 1 of 110
 Rare
Chester County 125
0% 0 of 125
 Rare
Sullivan County 38
0% 0 of 38
 Rare
Franklin County 23
0% 0 of 23
 Rare
Wyoming County 22
0% 0 of 22
 Rare
Somerset County 19
0% 0 of 19
 Rare
Centre County 13
0% 0 of 13
 Rare
Lancaster County 13
0% 0 of 13
 Rare
York County 12
0% 0 of 12
 Rare
Lebanon County 11
0% 0 of 11
 Rare
Union County 11
0% 0 of 11
 Rare

35 more Pennsylvania counties have 1 to 9 tested wells for arsenic, too few to rate.

Download this table (CSV) · Free to reuse under CC BY 4.0

Where to get your well tested for arsenic in Pennsylvania

1

Your county health department

Pennsylvania doesn't run a statewide free testing program that we know of. Some county health departments test wells or sell kits, so call yours first.

Pennsylvania's private well page
3

A mail-in kit

Fill the bottles at your kitchen tap and mail them back. We mark the kits that include arsenic.

Compare kits

Keep reading about wells in Pennsylvania

Questions people ask about arsenic in Pennsylvania

Is there arsenic in Pennsylvania well water?

Arsenic is widespread, over the limit in 15% or more of tested wells, in 1 of the 23 Pennsylvania counties with 10 or more tested wells. Across Pennsylvania, about 1 in 24 tested wells had arsenic over the EPA limit of 10 µg/L (52 of 1,247). Across all tested wells in the US it's about 1 in 9. That's less often than in the country as a whole. Counties still differ, so check yours below.

Where can I get my well tested for arsenic in Pennsylvania?

Use a lab certified by Pennsylvania for drinking water, or a mail-in kit that includes arsenic from a certified lab. Some county health departments test wells too, so call yours first.

See Pennsylvania's list of certified labs (a PDF list), or compare mail-in kits.

Where these numbers come from

  • Lab tests: Water Quality Portal (USGS and EPA), well samples since 2000. A well counts as over if any of its tests was over the EPA limit of 10 µg/L. Wells tested for studies and monitoring, not a random sample of homes.
  • Likely overstated: our own check of who tested the wells, when and where. How we check.
  • State programs and links: Department of Environmental Protection.