Arsenic is widespread in Franklin County wells.
1 widespread, 1 worth checking, 2 rare out of 4 health checks.
From 12 wells tested in Franklin County since 2000; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: nitrate (4), uranium (3), radon (3).
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
About 1 in 25 people 52,101 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
How deep wells go here
Middle depth: some shelter from the surface, not complete.
Well depths: US Groundwater Well Database
Radon risk (a gas from rock)
Likely here. Test your home's air first.
Radon zones: EPA map
Here's how Franklin County compares with Ohio and the counties around it.
Each result puts Franklin County next to the 6 counties that border it, on the chart's 0 to 50% scale.
This one is widespread in Franklin County wells.
Arsenic2 of 12 wells over
Too few tested to show: Delaware, Fairfield, Madison, Pickaway, Union.
This one is worth checking in Franklin County.
Lead1 of 12 wells over
Too few tested to show: Delaware, Fairfield, Madison, Pickaway, Union.
These 2 are rare in Franklin County.
Manganese0 of 12 wells over
Too few tested to show: Delaware, Fairfield, Madison, Pickaway, Union.
Fluoride0 of 12 wells over
Too few tested to show: Delaware, Fairfield, Madison, Pickaway, Union.
Too few Franklin County wells were tested for these 3.
Nitrate4 wells tested
Uranium3 wells tested
Radon in water3 wells tested
Coliform bacteria turned up in 2 of 3 tested Franklin County wells, so test for it every year.
Coliform bacteria2 of 3 wells had it
E. coli1 of 3 wells had it
E. coli means human or animal waste is getting in, so if a test of your Franklin County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 12 of 12 tested wells, and it isn't a health risk.
Iron stains12 of 12 wells had it
Too few tested to show: Delaware, Fairfield, Madison, Pickaway, Union.
Franklin County has 12 tested wells, and the busiest decade for testing was the 2010s.
None of the 12 wells has a test from 2020 or later, so a fresh test of your own well tells you more than any of these.
Most Franklin 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 4 things to check in Franklin County.
- Bacteria
- Nitrate
- Arsenic
- Lead
What Ohio offers well owners
- Free testingWe didn't find a free program for all of Ohio. Ohio's private well page
- Certified labsOhio's list of certified labs
- Well recordsOhio's well record search
Half the household wells here are shallower than 85 feet.
That comes from 17,638 household wells in Ohio's drilling records. Most wells of every kind here are 51 to 127 feet deep. Wells as deep as Franklin County's are usually better protected from fertilizer and bacteria at the surface, but they can pick up more of what's in the rock, like arsenic and uranium. Typical household wells here are shallower than in 47 of the 87 other Ohio counties with enough drilling records.
Look up your own well's depth in Ohio's well record search, or see how to find it.
Well depths: US Groundwater Well Database
Here's what we know about radon and PFAS in Franklin County.
Franklin 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 13 town water systems in Franklin County test for PFAS. 3 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 7.2 ng/L of PFOA. No well in Franklin 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 Franklin County
Is well water in Franklin County safe to drink?
2 of 12 wells tested in Franklin County had arsenic over the limit, about 2 in 10. Across Ohio it's about 2 in 10. That's a bigger share than in 8 of the 13 other Ohio counties with 10 or more tested wells. So test your own well for arsenic before you count on it.
Where can I get my well tested in Franklin County?
Use a lab Ohio has certified for drinking water. Ohio's list is linked above, in the box about testing. Ask for bacteria, nitrate, arsenic and lead, the tests that matter most in Franklin County.
How deep are wells in Franklin County?
Half the household wells here are shallower than 85 feet. Typical household wells here are shallower than in 47 of the 87 other Ohio counties with enough drilling records.
How does Franklin County compare with the counties around it?
For arsenic, the share of tested wells over the limit: Licking, the one neighbor with data, came in higher than Franklin County, at 53% against 17%. Groundwater doesn't stop at county lines, so Licking's 53% is worth knowing about if you live near it.
How often should I test my well in Franklin County?
In Franklin County, 2 of 3 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.
If you buy something through our links, we may earn a commission. We'd recommend the same thing either way, and we'll tell you when a free option exists. How we make money
Where the Franklin County numbers come from
- People on wells: 52,101 in Franklin County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 245 well water samples from 12 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2014.
- Well depths: 17,638 Ohio drilling records for Franklin County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 6 counties that share a border with Franklin County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 13 town water systems in Franklin County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Franklin County is zone 1 on the EPA Map of Radon Zones.
- State programs and links: Department of Health, checked November 1, 2026.