Nitrate and manganese have turned up often in Lancaster County wells, mostly from one small area.
2 likely overstated, 1 worth checking, 4 rare out of 7 health checks.
From 91 wells tested in Lancaster County since 2000; your own well needs its own test. How to read this
*Nitrate: All of these tests come from the US Geological Survey in one small part of the county, so this likely overstates it.
*Manganese: All of these tests come from the US Geological Survey in one small part of the county, so it may not match the rest of the county.
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
1 in 3 people 172,374 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
Radon risk (a gas from rock)
Likely here. Test your home's air first.
Radon zones: EPA map
Here's how Lancaster County compares with Pennsylvania and the counties around it.
Each result puts Lancaster County next to the 7 counties that border it, on the chart's 0 to 50% scale.
These 2 have turned up often here, mostly from one small area.
Nitrate45 of 90 wells over
* Likely overstated, so we don't rank it.
All of these tests come from the US Geological Survey in one small part of the county, so this likely overstates it.
Manganese9 of 43 wells over
* Likely overstated, so we don't rank it.
Too few tested to show: Harford, MD, Lebanon, York.
All of these tests come from the US Geological Survey in one small part of the county, so it may not match the rest of the county.
This one is worth checking in Lancaster County.
These 4 are rare in Lancaster County.
Arsenic0 of 13 wells over
Fluoride0 of 43 wells over
Lead0 of 27 wells over
Too few tested to show: Dauphin, Harford, MD, Lebanon, York.
Uranium0 of 43 wells over
Too few tested to show: Dauphin, Harford, MD, Lebanon, York.
Coliform bacteria turned up in 12 of 17 tested Lancaster County wells, so test for it every year.
Coliform bacteria12 of 17 wells had it
Too few tested to show: Cecil, MD, Harford, MD, Lebanon, York.
E. coli2 of 15 wells had it
Too few tested to show: Cecil, MD, Dauphin, Harford, MD, Lebanon, York.
E. coli means human or animal waste is getting in, so if a test of your Lancaster County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 3 of 43 tested wells, and it isn't a health risk.
Iron stains3 of 43 wells had it
Too few tested to show: Lebanon, York.
Lancaster County has 91 tested wells, and the busiest decade for testing was the 2010s.
Only 13 of the 91 wells have a test from 2020 or later, so a fresh test of your own well tells you more than any of these.
Most Lancaster County wells in these records were tested for research or because someone suspected a problem, which can push the shares above what a typical home well would show (how we read the numbers).
One mail-in lab test covers the 5 things to check in Lancaster County.
- Bacteria
- Nitrate
- Manganese
- Radon in water
- Arsenic
What Pennsylvania offers well owners
- Free testingWe didn't find a free program for all of Pennsylvania. Pennsylvania's private well page
- Certified labsPennsylvania's list of certified labs
- Well recordsPennsylvania's well record search
Here's what we know about radon and PFAS in Lancaster County.
Lancaster County is in the EPA's highest radon zone. Radon from well water adds to the radon in your indoor air, so test your air first, and your water too if the air is high. Radon guide
Between 2023 and 2025 the EPA had 21 town water systems in Lancaster County test for PFAS. 14 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 24 ng/L of PFOA. No well in Lancaster County has public PFAS results, so the town systems are the best clue to what's in the groundwater nearby. PFAS guide
Radon zones: EPA Map of Radon Zones. PFAS: EPA tests of town water systems, 2023 to 2025
Questions people ask about well water in Lancaster County
Is well water in Lancaster County safe to drink?
45 of 90 wells tested in Lancaster County had nitrate over the limit, about 5 in 10. Across Pennsylvania it's about 1 in 12. We don't rank this against other Pennsylvania counties, because most of these tests come from one small area. All of these tests come from the US Geological Survey in one small part of the county, so this likely overstates it. So test your own well for nitrate before you count on it.
Where can I get my well tested in Lancaster County?
Use a lab Pennsylvania has certified for drinking water. Pennsylvania's list is linked above, in the box about testing. Ask for bacteria, nitrate, manganese, radon in water and arsenic, the tests that matter most in Lancaster County.
How does Lancaster County compare with the counties around it?
For nitrate, the share of tested wells over the limit: Lancaster County, at 50%, had a higher share than all 7 neighboring counties with data. Groundwater doesn't stop at county lines, so Chester's 14% is worth knowing about if you live near it.
How often should I test my well in Lancaster County?
In Lancaster County, 12 of 17 tested wells had coliform bacteria, so the CDC's advice matters here: test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.
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Where the Lancaster County numbers come from
- People on wells: 172,374 in Lancaster County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 1,480 well water samples from 91 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2022.
- Neighboring counties: the 7 counties that share a border with Lancaster County, from the Census Bureau's county adjacency file.
- Results marked likely overstated: our own check of who tested the wells, when and where.
- PFAS: EPA tests of 21 town water systems in Lancaster County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Lancaster County is zone 1 on the EPA Map of Radon Zones.
- State programs and links: Department of Environmental Protection, checked November 1, 2026.