Arsenic is widespread in Cleveland County wells.

1 widespread, 1 worth checking, 4 rare out of 6 health checks.

From 245 wells tested in Cleveland County since 2000; your own well needs its own test. How to read this

Tested wells over the limit ClevelandOklahoma

Arsenic55%36 of 65 Uranium12%3 of 24 Manganese3%3 of 103 Fluoride1%1 of 159 Nitrate0%0 of 158 Lead0%0 of 13

GermsTest every year, whatever the chart says

Coliform bacteria0%0 of 1 E. coli0%0 of 1

StainsNot a health risk

Iron stains17%17 of 101

Not charted, because fewer than 10 wells were tested: radon (1).

Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+

Lab results: Water Quality Portal (USGS and EPA)

Show bacteria and iron

Who drinks from a well here

1 in 7 people 44,875 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)

LowMiddleHigh

Less likely, but the EPA still says test your air.

Radon zones: EPA map

Here's how Cleveland County compares with Oklahoma and the counties around it.

Each result puts Cleveland County next to the 4 counties that border it, on the chart's 0 to 50% scale.

This one is widespread in Cleveland County wells.

Arsenic36 of 65 wells over

About 6 in 10 wells tested here from 2000 to 2018 were over the EPA limit of 10 µg/L, against about 2 in 10 across Oklahoma. Half the results were under 16 µg/L, and the top 1 in 10 were 74 µg/L or more. That's the highest share among the 7 Oklahoma counties with 10 or more tested wells.

Cleveland and its neighbors

Cleveland55%

Oklahoma19%

Pottawatomie2%

Too few tested to show: Canadian, McClain.

Arsenic guide

This one is worth checking in Cleveland County.

Uranium3 of 24 wells over

3 of 24 wells tested here from 2000 to 2018 were over the EPA limit of 30 µg/L, against about 1 in 11 across Oklahoma. At least half the results were too low for the lab to measure, and the top 1 in 10 were 67 µg/L or more. That's a bigger share than in 3 of the 4 other Oklahoma counties with 10 or more tested wells.

Cleveland and its neighbors

Pottawatomie16%

Cleveland12%

Too few tested to show: Canadian, McClain, Oklahoma.

Uranium guide

These 4 are rare in Cleveland County.

Manganese3 of 103 wells over

3 of 103 wells tested here from 2000 to 2018 were over the EPA health advisory of 0.3 mg/L, against about 1 in 21 across Oklahoma. Half the results were under 0.005 mg/L, and the top 1 in 10 were 0.01 mg/L or more. That's a bigger share than in 22 of the 31 other Oklahoma counties with 10 or more tested wells, leaving out 1 county whose results are likely overstated.

Cleveland and its neighbors

Canadian32%

Pottawatomie9%

Oklahoma6%

Cleveland3%

* Likely overstated, so we don't rank it.

Too few tested to show: McClain.

Manganese guide

Fluoride1 of 159 wells over

1 of 159 wells tested here from 2000 to 2018 was over the EPA limit of 4 mg/L, against under 1 in 100 across Oklahoma. Half the results were under 0.29 mg/L, and the top 1 in 10 were 0.6 mg/L or more. That's a bigger share than in 30 of the 32 other Oklahoma counties with 10 or more tested wells.

Cleveland and its neighbors

Cleveland1%

Canadian0%

Oklahoma0%

Pottawatomie0%

Too few tested to show: McClain.

Nitrate0 of 158 wells over

None of the 158 wells tested here from 2000 to 2018 were over the EPA limit of 10 mg/L, against about 1 in 8 across Oklahoma. Half the results were under 0.29 mg/L, and the top 1 in 10 were 0.69 mg/L or more. Cleveland County had none, while 30 of the 39 other Oklahoma counties with 10 or more tested wells had at least one.

Cleveland and its neighbors

Canadian15%

Pottawatomie4%

Oklahoma1%

Cleveland0%

Too few tested to show: McClain.

Nitrate guide

Lead0 of 13 wells over

None of the 13 wells tested here from 2000 to 2018 were over the EPA action level of 15 µg/L, against none across Oklahoma. Cleveland County had none, and neither did any of the 4 other Oklahoma counties with 10 or more tested wells.

Cleveland and its neighbors

Cleveland0%

Pottawatomie0%

Too few tested to show: Canadian, McClain, Oklahoma.

Lead guide

Too few Cleveland County wells were tested for this one.

Radon in water1 well tested

Only 1 well here was tested in 2018, too few to say how common it is. Across Oklahoma it's none.

Radon guide

None of the 1 Cleveland County wells tested for bacteria had it, but every well needs a yearly test.

Coliform bacteria0 of 1 wells had it

None of the 1 wells tested here in 2018 had coliform bacteria, against about 3 in 10 across Oklahoma.

Bacteria guide

E. coli0 of 1 wells had it

None of the 1 wells tested here in 2018 had E. coli, against about 1 in 7 across Oklahoma.

E. coli means human or animal waste is getting in, so if a test of your Cleveland County well finds it, boil drinking water until the well is fixed.

Bacteria guide

Iron reached staining levels in 17 of 101 tested wells, and it isn't a health risk.

Iron stains17 of 101 wells had it

About 2 in 10 wells tested here from 2000 to 2018 had enough iron to stain (0.3 mg/L), against about 1 in 7 across Oklahoma.

Cleveland and its neighbors

Canadian64%

Cleveland17%

Oklahoma9%

Pottawatomie8%

Too few tested to show: McClain.

Iron guide

Most of the 245 wells tested in Cleveland County were last tested before 2010.

242 wells had a test in the 2000s and 9 in the 2010s.

An old result shows the water as it was then, so treat these 245 wells as a starting point and test your own.

Most Cleveland 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 Cleveland County.

Bacteria
Nitrate
Arsenic
Uranium

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 6,490 household wells in Oklahoma's drilling records. Most wells of every kind here are 45 to 200 feet deep. Wells as deep as Cleveland 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 Cleveland County.

Cleveland 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 4 town water systems in Cleveland County test for PFAS. 2 found some PFAS, all below the new limits. No well in Cleveland 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

Next door to Cleveland County

Oklahoma Pottawatomie

Elsewhere in Oklahoma

Logan Garfield

All of Oklahoma

Questions people ask about well water in Cleveland County

Is well water in Cleveland County safe to drink?

36 of 65 wells tested in Cleveland County had arsenic over the limit, about 6 in 10. Across Oklahoma it's about 2 in 10. That's the highest share among the 7 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 Cleveland 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 uranium, the tests that matter most in Cleveland County.

How deep are wells in Cleveland 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 Cleveland County compare with the counties around it?

For arsenic, the share of tested wells over the limit: Cleveland County, at 55%, had a higher share than all 2 neighboring counties with data. Groundwater doesn't stop at county lines, so Oklahoma's 19% is worth knowing about if you live near it.

How often should I test my well in Cleveland County?

None of the 1 wells tested for bacteria in Cleveland County had it, but the CDC still says to test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.

By the Tested Water teamData from the USGS, EPA and Department of Environmental QualityUpdated November 8, 2026

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Where the Cleveland County numbers come from

People on wells: 44,875 in Cleveland County, from EPA estimates built on the 2020 Census (Murray et al.).
Lab tests: 1,356 well water samples from 245 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2018.
Well depths: 6,490 Oklahoma drilling records for Cleveland County, gathered in the US Groundwater Well Database (Lin and others, 2024).
Neighboring counties: the 4 counties that share a border with Cleveland County, from the Census Bureau's county adjacency file.
PFAS: EPA tests of 4 town water systems in Cleveland County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
Radon: Cleveland County is zone 3 on the EPA Map of Radon Zones.
State programs and links: Department of Environmental Quality, checked November 1, 2026.

Download this county's data (CSV)How we read these numbers Report an error