Arsenic is worth checking in Oakland County wells.
1 worth checking, 5 rare out of 6 health checks.
From 58 wells tested in Oakland County since 2000; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: 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
1 in 5 people 260,146 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)
Possible here. A home air test is inexpensive.
Radon zones: EPA map
Here's how Oakland County compares with Michigan and the counties around it.
Each result puts Oakland County next to the 6 counties that border it, on the chart's 0 to 50% scale.
This one is worth checking in Oakland County.
Arsenic2 of 32 wells over
Too few tested to show: Genesee, Lapeer, Macomb, Wayne.
These 5 are rare in Oakland County.
Nitrate2 of 56 wells over
Too few tested to show: Genesee, Lapeer, Macomb, Wayne.
Manganese2 of 57 wells over
Too few tested to show: Genesee, Lapeer, Macomb, Wayne.
Uranium0 of 32 wells over
Too few tested to show: Genesee, Lapeer, Macomb, Wayne.
Lead0 of 32 wells over
Too few tested to show: Genesee, Lapeer, Macomb, Wayne.
Fluoride0 of 57 wells over
Too few tested to show: Genesee, Lapeer, Macomb, Wayne.
Too few Oakland County wells were tested for this one.
Radon in water3 wells tested
Coliform bacteria turned up in 4 of 31 tested Oakland County wells, so test for it every year.
Coliform bacteria4 of 31 wells had it
E. coli1 of 31 wells had it
E. coli means human or animal waste is getting in, so if a test of your Oakland County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 38 of 57 tested wells, and it isn't a health risk.
Iron stains38 of 57 wells had it
Too few tested to show: Genesee, Lapeer, Macomb, Wayne.
Most of the 58 wells tested in Oakland County were last tested before 2010.
An old result shows the water as it was then, so treat these 58 wells as a starting point and test your own.
Most Oakland 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 3 things to check in Oakland County.
- Bacteria
- Nitrate
- Arsenic
What Michigan offers well owners
- Free testingWe didn't find a free program for all of Michigan. Michigan's private well page
- Certified labsMichigan's list of certified labs
- Well recordsMichigan's well record search
- New wellsEGLE's well testing page says a private well was required to be tested when it was first installed.
Half the household wells here are shallower than 88 feet.
That comes from 59,637 household wells in Michigan's drilling records. Most wells of every kind here are 64 to 127 feet deep. Wells as deep as Oakland 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 46 of the 82 other Michigan counties with enough drilling records.
Look up your own well's depth in Michigan'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 Oakland County.
Oakland County is in the EPA's middle radon zone. An indoor air test is cheap and tells you whether to look at your water. Radon guide
Between 2023 and 2025 the EPA had 40 town water systems in Oakland County test for PFAS. 1 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 10 ng/L of PFOS. No well in Oakland 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 Oakland County
Is well water in Oakland County safe to drink?
2 of 32 wells tested in Oakland County had arsenic over the limit, about 1 in 16. Across Michigan it's about 1 in 19. That's a bigger share than in 2 of the 3 other Michigan 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 Oakland County?
Use a lab Michigan has certified for drinking water. Michigan's list is linked above, in the box about testing. Ask for bacteria, nitrate and arsenic, the tests that matter most in Oakland County.
How deep are wells in Oakland County?
Half the household wells here are shallower than 88 feet. Typical household wells here are shallower than in 46 of the 82 other Michigan counties with enough drilling records.
How does Oakland County compare with the counties around it?
For arsenic, the share of tested wells over the limit: 1 of the 2 neighboring counties with data had a higher share than Oakland County, at 6%. Livingston had the most, at 9%. Groundwater doesn't stop at county lines, so Livingston's 9% is worth knowing about if you live near it.
How often should I test my well in Oakland County?
In Oakland County, 4 of 31 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 Oakland County numbers come from
- People on wells: 260,146 in Oakland County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 812 well water samples from 58 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2023.
- Well depths: 59,637 Michigan drilling records for Oakland County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 6 counties that share a border with Oakland County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 40 town water systems in Oakland County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Oakland County is zone 2 on the EPA Map of Radon Zones.
- State programs and links: Michigan Department of Environment, Great Lakes, and Energy (EGLE), checked November 1, 2026.