About 19% of the county's 149,568 residents. Rank 32 of 83 in Michigan.
95% range 4,071 to 7,667 private-well users (2010 base year). Rank 12 of 83 in Michigan.
Moderate potential (average indoor radon may be between 2 and 4 pCi/L). EPA says the map should not be used to decide whether an individual home needs testing.
Labs with an address in this county, from the official state lists on this site, matched by ZIP code.
What to test for in Monroe County
Private wells are not regulated like public water: EPA advises owners to test their well every year for total coliform bacteria, nitrates, total dissolved solids and pH. Your state's own schedule:
- Michigan EGLE's drinking water lab lists times people may want to test their water, especially from a private well: when they notice an unusual color, odor or appearance, when a new well is installed, and during routine maintenance of an old well or well pump. source
Arsenic. USGS estimates that about 5,370 people using private wells in Monroe County had arsenic above 10 µg/L, EPA's limit for public water (2010 base year; 95% range 4,071 to 7,667). USGS describes this kind of estimate as useful "for broad screening of the population at risk", so it says nothing certain about any one well. Arsenic has no taste or smell: test for it by name.
Radon. EPA puts Monroe County in Zone 2: moderate potential (average indoor radon may be between 2 and 4 pCi/L). That map is about radon in indoor air, and EPA says it should not be used to decide whether an individual home needs testing. If radon is found in your air and you have a well, EPA suggests testing the water too: see radon in well water.
For anything specific to your home (farms nearby, old plumbing, a new baby, a smell or stain), use the which-tests checklist. When the results arrive, check your numbers against EPA's limits.
Show the numbers
| Item | Value | Note |
|---|---|---|
| Tuscola County | 11,252 people (2010 base year) | |
| Clinton County | 8,229 people (2010 base year) | |
| Livingston County | 7,681 people (2010 base year) | |
| Oakland County | 7,540 people (2010 base year) | |
| Genesee County | 6,942 people (2010 base year) | |
| Monroe County (this county) | 5,370 people (2010 base year) |
USGS model estimate for broad screening, not a measurement of any well. Only a test tells you about your own well. Source: USGS, Estimated county level domestic well population with arsenic greater than 10 micrograms per liter (Ayotte, Medalie and Qi, 2017), accessed 2026-11-01.
PFAS in public water near Monroe County (public supply, not your well)
This is public water data, not your well. A private well draws its own groundwater, which can have more or less PFAS than the public supply nearby. Only a test of your well tells you.
Under EPA’s fifth Unregulated Contaminant Monitoring Rule (UCMR 5), public water systems sampled their water for 29 PFAS between Jan 3, 2023 and Jun 17, 2026. 10 public systems that serve ZIP codes mainly in Monroe County reported results. 1 of them had at least one sample with PFOA or PFOS at or above 4.0 ng/L, and 3 had at least one of the 29 PFAS measured at or above its reporting level.
| Public water system | System ID | Highest PFOA (ng/L) | Highest PFOS (ng/L) |
|---|---|---|---|
| Dundee | MI0001880 | 13 |
4.0 ng/L (parts per trillion) is both EPA’s UCMR 5 reporting level for PFOA and PFOS and the number in EPA’s 2024 limit for public water. That limit is judged on a running annual average, so one sample at that level is not a violation. EPA proposed changes to its PFAS rules in May 2026: see PFAS in well water for the current status and who should test a well. To test your own well, find a lab certified for PFAS.
Method: a system counts for this county when it reports serving a ZIP code whose largest land part is in this county, so a system serving several counties counts in each. Source: U.S. EPA, UCMR 5 occurrence data (by state), file dated Oct 15, 2026; downloaded Nov 1, 2026.
Testing programs and help in Michigan
- EGLE says to contact your local health department for a recommendation on what to test for, since recommendations may differ by area, household and your own concerns. EGLE lists coliforms, nitrites and some metals (like arsenic and lead) as standard concerns for private wells, and notes that U.S. EPA recommends testing all private wells at a minimum for coliform bacteria and nitrate/nitrite. source
- The EGLE lab does not interpret test results. For questions about your water quality, EGLE refers you to your local health department; for private wells it also points to the Be Well Informed online tool. source
Buying a home with a well in Monroe County
Loan test (FHA, VA, USDA) in Monroe County, MI
- VA. Test results are valid for 90 days from the date the local health authority certifies them, unless the local authority says otherwise. VA’s chapter names no list of contaminants: the water must meet the local health authority’s requirements, or EPA guidelines where it has none. Your lender may ask for specific tests.
- FHA. A well test is required in the situations FHA’s handbook lists, among others, and the report may not be more than 180 days old at disbursement.
- USDA. Guaranteed loans need a water quality test for a private well, done by the local health authority or a state-certified lab, and no more than 180 days old at closing.
Lenders can ask for more (extra tests, a particular lab, who takes the sample): ask your lender before you book. Federal rules as read on Nov 3, 2026 source 1 source 2 source 3. Full comparison: VA, FHA and USDA well water test requirements. Loan test kits sold by mail, with price and days to results: kits compared.
State-certified labs in Monroe County
Dundee Water Filtration Plant
350 West Monroe Street, Dundee, MIPublic samples: ask the labFrenchtown Charter Township
5300 North Dixie Highway, Newport, MIPublic samples: ask the labMonroe Water Filtration Plant
915 East Front Street, Monroe, MIPublic samples: ask the labSouth County Water System - Monroe
9489 Lewis Avenue, Temperance, MIPublic samples: ask the labWhiteford Water Treatment Plant
8000 Yankee Rd, Ottawa Lake, MIPublic samples: ask the labTesting by mail from Monroe County. Michigan EGLE Drinking Water Laboratory, Preview: Water Testing Fee Schedule, pricing effective Oct 1, 2026 publishes these prices: Total coliform and E. coli $23; Nitrate and nitrite $41; Partial chemistry: calcium, chloride, fluoride, hardness, iron, magnesium, nitrate, nitrite, sodium and sulfate $66 (plus a $13 per-sample preparation fee) (checked 3 Nov 2026) source. All Michigan state-lab prices and how to get a kit.
Labs on the Michigan list whose own websites say they take homeowner samples: Aqua Test Laboratories (White Lake), Biosan (Warren), Enviro Lab Services, Inc (Oscoda), Garrett Laboratories, Inc. (Niles), Grand Traverse Analytical, LLC (Traverse City), LMAS Regional Laboratory (Newberry), Northwest Michigan Community Health Agency (Gaylord), OML Analytical (Rockford) and 8 more. Use Check my ZIP to sort labs by distance.
See all Michigan labs in the finder and filter by the test you need and by labs that take homeowner samples.
- USGS, Estimated use of water in the United States, county-level data for 2015 (Dieter et al., ver. 2.0, 2018)
- USGS, Estimated county level domestic well population with arsenic greater than 10 micrograms per liter (Ayotte, Medalie and Qi, 2017)
- U.S. EPA, Map of Radon Zones, county list (EPA 402/A-16/001)
- U.S. Census Bureau, 2020 ZCTA to county relationship file (lab ZIP codes to counties)
- EGLE - State of Michigan Certified Laboratories: Chemistry + EGLE - State of Michigan Certified Laboratories: Microbiological + EGLE - State of Michigan Certified Laboratories: Lead and Copper + EGLE - Certified Radiological Laboratories + EGLE - In-State Certified PFAS Laboratories (SOM Certified Labs - Chemistry 3/11/2026 (chemistry, microbiological, lead and copper lists); 9/8/2025 (radiological, in-state PFAS lists))
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