Manganese is worth checking in Waukesha County wells.
1 worth checking, 6 rare out of 7 health checks.
From 29 wells tested in Waukesha 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 3 people 150,151 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)
Likely here. Test your home's air first.
Radon zones: EPA map
Here's how Waukesha County compares with Wisconsin and the counties around it.
Each result puts Waukesha County next to the 7 counties that border it, on the chart's 0 to 50% scale.
This one is worth checking in Waukesha County.
Manganese1 of 18 wells over
These 6 are rare in Waukesha County.
Nitrate1 of 28 wells over
Too few tested to show: Milwaukee, Ozaukee.
Arsenic0 of 18 wells over
Lead0 of 16 wells over
Uranium0 of 16 wells over
Radon in water0 of 13 wells over
Fluoride0 of 16 wells over
Every well needs a bacteria test every year.
No bacteria tests from Waukesha County wells are in the public data. Test every year anyway.
Iron reached staining levels in 7 of 18 tested wells, and it isn't a health risk.
Iron stains7 of 18 wells had it
About 3 in 10 of the 29 wells tested in Waukesha County have a test from 2020 or later.
With 9 wells tested since 2020, age matters less here than who did the testing and why.
Most Waukesha 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 Waukesha County.
- Bacteria
- Nitrate
- Manganese
- Arsenic
What Wisconsin offers well owners
- Free testingWe didn't find a free program for all of Wisconsin. Wisconsin's private well page
- Certified labsWisconsin's list of certified labs
- Well recordsWisconsin's well record search
- New wellsUnder NR 812.46, the well driller must collect a water sample from any new or reconstructed potable well within 30 days of completion and have it tested for coliform bacteria by a certified lab.
Half the wells on record here are shallower than 150 feet.
That comes from 22,667 wells in Wisconsin's drilling records. Most wells of every kind here are 83 to 223 feet deep. Wells as deep as Waukesha 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 wells on record here go deeper than in 52 of the 71 other Wisconsin counties with enough drilling records.
Look up your own well's depth in Wisconsin'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 Waukesha County.
Waukesha 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 Waukesha 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 12 ng/L of PFOS. No well in Waukesha 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 Waukesha County
Is well water in Waukesha County safe to drink?
1 of 18 wells tested in Waukesha County had manganese over the limit, about 1 in 18. Across Wisconsin it's about 1 in 15. That's a bigger share than in 4 of the 6 other Wisconsin counties with 10 or more tested wells, leaving out 1 county whose results are likely overstated. So test your own well for manganese before you count on it.
Where can I get my well tested in Waukesha County?
Use a lab Wisconsin has certified for drinking water. Wisconsin's list is linked above, in the box about testing. Ask for bacteria, nitrate, manganese and arsenic, the tests that matter most in Waukesha County.
How deep are wells in Waukesha County?
Half the wells on record here are shallower than 150 feet. Typical wells on record here go deeper than in 52 of the 71 other Wisconsin counties with enough drilling records.
How does Waukesha County compare with the counties around it?
For nitrate, the share of tested wells over the limit: 4 of the 5 neighboring counties with data had a higher share than Waukesha County, at 4%. Dodge had the most, at 33%. Groundwater doesn't stop at county lines, so Dodge's 33% is worth knowing about if you live near it.
How often should I test my well in Waukesha County?
Waukesha 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 Waukesha County numbers come from
- People on wells: 150,151 in Waukesha County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 279 well water samples from 29 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2023.
- Well depths: 22,667 Wisconsin drilling records for Waukesha County, gathered in the US Groundwater Well Database (Lin and others, 2024).
- Neighboring counties: the 7 counties that share a border with Waukesha County, from the Census Bureau's county adjacency file.
- Nitrate for comparison: Wisconsin DATCP, Agricultural Chemicals in Wisconsin Groundwater (2017).
- PFAS: EPA tests of 13 town water systems in Waukesha County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Waukesha County is zone 1 on the EPA Map of Radon Zones.
- State programs and links: Department of Natural Resources (DNR), checked November 1, 2026.