Arsenic is widespread in Oklahoma County wells.
1 widespread, 1 worth checking, 2 rare out of 4 health checks.
From 174 wells tested in Oklahoma County since 2002; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: uranium (5), lead (5).
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 10 people 80,195 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
How deep wells go here
Deep wells: fewer surface germs, more minerals from the rock.
Well depths: US Groundwater Well Database
Radon risk (a gas from rock)
Less likely, but the EPA still says test your air.
Radon zones: EPA map
Here's how Oklahoma County compares with Oklahoma and the counties around it.
Each result puts Oklahoma County next to the 6 counties that border it, on the chart's 0 to 50% scale.
This one is widespread in Oklahoma County wells.
Arsenic8 of 42 wells over
Too few tested to show: Canadian, Kingfisher, Logan.
This one is worth checking in Oklahoma County.
Manganese10 of 174 wells over
* Likely overstated, so we don't rank it.
These 2 are rare in Oklahoma County.
Nitrate1 of 157 wells over
Fluoride0 of 160 wells over
Too few Oklahoma County wells were tested for these 2.
Uranium5 wells tested
Lead5 wells tested
Every well needs a bacteria test every year.
No bacteria tests from Oklahoma County wells are in the public data. Test every year anyway.
Iron reached staining levels in 16 of 174 tested wells, and it isn't a health risk.
Iron stains16 of 174 wells had it
Most of the 174 wells tested in Oklahoma County were last tested before 2010.
An old result shows the water as it was then, so treat these 174 wells as a starting point and test your own.
Most Oklahoma 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 Oklahoma County.
- Bacteria
- Nitrate
- Arsenic
- Manganese
What Oklahoma offers well owners
- Free testingWe didn't find a free program for all of Oklahoma. Oklahoma's private well page
- Certified labsOklahoma's list of certified labs
- Well recordsOklahoma's well record search
Half the household wells here are shallower than 180 feet.
That comes from 10,067 household wells in Oklahoma's drilling records. Most wells of every kind here are 22 to 200 feet deep. Wells as deep as Oklahoma 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 go deeper than in 62 of the 75 other Oklahoma counties with enough drilling records.
Look up your own well's depth in Oklahoma'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 Oklahoma County.
Oklahoma County is in the EPA's lowest radon zone, so radon from well water is unlikely to be a problem. Radon guide
Between 2023 and 2025 the EPA had 12 town water systems in Oklahoma County test for PFAS. 2 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 6.4 ng/L of PFOS. No well in Oklahoma 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 Oklahoma County
Is well water in Oklahoma County safe to drink?
8 of 42 wells tested in Oklahoma County had arsenic over the limit, about 2 in 10. Across Oklahoma it's about 2 in 10. That's a bigger share than in 5 of the 6 other Oklahoma 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 Oklahoma County?
Use a lab Oklahoma has certified for drinking water. Oklahoma's list is linked above, in the box about testing. Ask for bacteria, nitrate, arsenic and manganese, the tests that matter most in Oklahoma County.
How deep are wells in Oklahoma County?
Half the household wells here are shallower than 180 feet. Typical household wells here go deeper than in 62 of the 75 other Oklahoma counties with enough drilling records.
How does Oklahoma County compare with the counties around it?
For arsenic, the share of tested wells over the limit: 1 of the 3 neighboring counties with data had a higher share than Oklahoma County, at 19%. Cleveland had the most, at 55%. Groundwater doesn't stop at county lines, so Cleveland's 55% is worth knowing about if you live near it.
How often should I test my well in Oklahoma County?
Oklahoma County has no public bacteria results for wells, so follow the CDC's advice: 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 Oklahoma County numbers come from
- People on wells: 80,195 in Oklahoma County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 1,342 well water samples from 174 wells in the Water Quality Portal, run by the USGS and EPA, 2002 to 2013.
- Well depths: 10,067 Oklahoma drilling records for Oklahoma County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 6 counties that share a border with Oklahoma County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 12 town water systems in Oklahoma County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Oklahoma County is zone 3 on the EPA Map of Radon Zones.
- State programs and links: Department of Environmental Quality, checked November 1, 2026.