Nitrate is worth checking in Washtenaw County wells.
1 worth checking, 5 rare out of 6 health checks.
From 13 wells tested in Washtenaw County since 2000; your own well needs its own test. How to read this
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 76,932 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 Washtenaw County compares with Michigan and the counties around it.
Each result puts Washtenaw County next to the 6 counties that border it, on the chart's 0 to 50% scale.
This one is worth checking in Washtenaw County.
Nitrate1 of 13 wells over
Too few tested to show: Jackson, Lenawee, Monroe, Wayne.
These 5 are rare in Washtenaw County.
Arsenic0 of 10 wells over
Too few tested to show: Jackson, Lenawee, Monroe, Wayne.
Manganese0 of 13 wells over
Too few tested to show: Jackson, Lenawee, Monroe, Wayne.
Uranium0 of 10 wells over
Too few tested to show: Jackson, Lenawee, Monroe, Wayne.
Lead0 of 10 wells over
Too few tested to show: Jackson, Lenawee, Monroe, Wayne.
Fluoride0 of 13 wells over
Too few tested to show: Jackson, Lenawee, Monroe, Wayne.
Coliform bacteria turned up in 2 of 6 tested Washtenaw County wells, so test for it every year.
Coliform bacteria2 of 6 wells had it
E. coli1 of 6 wells had it
E. coli means human or animal waste is getting in, so if a test of your Washtenaw County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 7 of 13 tested wells, and it isn't a health risk.
Iron stains7 of 13 wells had it
Too few tested to show: Jackson, Lenawee, Monroe, Wayne.
Washtenaw County has 13 tested wells, and the busiest decade for testing was the 2000s.
None of the 13 wells has a test from 2020 or later, so a fresh test of your own well tells you more than any of these.
Most Washtenaw 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 Washtenaw 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 91 feet.
That comes from 19,084 household wells in Michigan's drilling records. Most wells of every kind here are 66 to 130 feet deep. Wells as deep as Washtenaw 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 41 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 Washtenaw County.
Washtenaw 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 10 town water systems in Washtenaw County test for PFAS. 3 found some PFAS, all below the new limits. No well in Washtenaw 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 Washtenaw County
Is well water in Washtenaw County safe to drink?
1 of 13 wells tested in Washtenaw County had nitrate over the limit, about 1 in 13. Across Michigan it's about 1 in 26. 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 nitrate before you count on it.
Where can I get my well tested in Washtenaw 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 Washtenaw County.
How deep are wells in Washtenaw County?
Half the household wells here are shallower than 91 feet. Typical household wells here are shallower than in 41 of the 82 other Michigan counties with enough drilling records.
How does Washtenaw County compare with the counties around it?
For nitrate, the share of tested wells over the limit: 1 of the 2 neighboring counties with data had a higher share than Washtenaw County, at 8%. Livingston had the most, at 13%. Groundwater doesn't stop at county lines, so Livingston's 13% is worth knowing about if you live near it.
How often should I test my well in Washtenaw County?
In Washtenaw County, 2 of 6 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 Washtenaw County numbers come from
- People on wells: 76,932 in Washtenaw County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 191 well water samples from 13 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2016.
- Well depths: 19,084 Michigan drilling records for Washtenaw County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 6 counties that share a border with Washtenaw County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 10 town water systems in Washtenaw County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Washtenaw County is zone 1 on the EPA Map of Radon Zones.
- State programs and links: Michigan Department of Environment, Great Lakes, and Energy (EGLE), checked November 1, 2026.