Private wells
Michigan well water: who's on a well and what to test for
People on private wells
3,023,300
Homes on wells
31.6%
Est. above arsenic limit
192,700
Every Michigan county
Sorted by people on private wells. Arsenic and nitrate are modeled for typical wells in the county, not measured at yours; depth is the median of domestic well records.
| Oakland County | 260,100 | 19% | 5.6% | 0.1 | 88 ft |
| Genesee County | 176,600 | 41% | 29.5% | 0.0 | 180 ft |
| Kent County | 165,700 | 23% | 8.3% | 1.0 | 86 ft |
| Livingston County | 114,200 | 57% | 7.1% | 0.1 | 85 ft |
| Ottawa County | 86,300 | 29% | 3.5% | 0.5 | 84 ft |
| Kalamazoo County | 81,600 | 29% | 2.4% | 1.2 | 84 ft |
| Allegan County | 79,800 | 64% | 5.1% | 0.8 | 85 ft |
| Jackson County | 79,300 | 51% | 5.2% | 0.3 | 119 ft |
| Muskegon County | 79,000 | 44% | 9.4% | 0.7 | 46 ft |
| Washtenaw County | 76,900 | 19% | 12.1% | 0.1 | 90 ft |
| Berrien County | 71,200 | 45% | 5.5% | 0.6 | 98 ft |
| Calhoun County | 64,400 | 47% | 6.4% | 1.0 | 100 ft |
| Lapeer County | 62,400 | 70% | 56.5% | 0.0 | 181 ft |
| Van Buren County | 53,500 | 69% | 2.4% | 0.9 | 78 ft |
| Grand Traverse County | 52,900 | 54% | 3.5% | 1.0 | 108 ft |
| St. Clair County | 52,200 | 30% | 16.0% | 0.0 | 102 ft |
| Monroe County | 50,500 | 31% | 6.0% | 0.0 | 80 ft |
| Ingham County | 48,300 | 16% | 6.7% | 0.1 | 150 ft |
| Eaton County | 47,700 | 41% | 24.8% | 0.1 | 138 ft |
| Barry County | 46,900 | 77% | 12.2% | 0.7 | 81 ft |
| Lenawee County | 46,500 | 49% | 8.3% | 0.1 | 90 ft |
| Saginaw County | 45,900 | 22% | 45.5% | 0.0 | 118 ft |
| Montcalm County | 44,600 | 73% | 5.2% | 1.7 | 74 ft |
| Clinton County | 42,200 | 51% | 29.8% | 0.0 | 220 ft |
| Macomb County | 41,400 | 4% | 9.8% | 0.1 | 74 ft |
| Cass County | 40,000 | 80% | 3.6% | 2.1 | 83 ft |
| Wayne County | 39,400 | 2% | 3.2% | 0.0 | 97 ft |
| Shiawassee County | 39,300 | 55% | 38.4% | 0.0 | 135 ft |
| Newaygo County | 39,200 | 81% | 2.3% | 1.1 | 73 ft |
| Tuscola County | 36,400 | 67% | 36.2% | 0.0 | 180 ft |
| Ionia County | 35,900 | 58% | 7.3% | 0.8 | 106 ft |
| Midland County | 34,400 | 39% | 20.3% | 0.0 | 97 ft |
| St. Joseph County | 33,700 | 57% | 2.1% | 1.2 | 68 ft |
| Isabella County | 31,800 | 49% | 22.6% | 0.2 | 85 ft |
| Hillsdale County | 30,300 | 69% | 7.5% | 0.2 | 87 ft |
| Mecosta County | 29,800 | 76% | 2.1% | 1.4 | 72 ft |
| Sanilac County | 25,900 | 60% | 29.5% | 0.0 | 104 ft |
| Clare County | 25,000 | 86% | 1.9% | 0.4 | 82 ft |
| Branch County | 24,900 | 62% | 4.2% | 0.4 | 62 ft |
| Bay County | 22,700 | 20% | 16.0% | 0.0 | 135 ft |
| Marquette County | 22,100 | 39% | 2.4% | 0.1 | 76 ft |
| Wexford County | 21,100 | 64% | 1.7% | 1.0 | 110 ft |
| Gladwin County | 21,000 | 87% | 5.6% | 0.1 | 90 ft |
| Roscommon County | 20,200 | 89% | 2.1% | 0.2 | 89 ft |
| Oceana County | 20,200 | 79% | 3.7% | 0.9 | 68 ft |
| Gratiot County | 19,600 | 53% | 49.9% | 0.1 | 110 ft |
| Emmet County | 19,300 | 54% | 2.5% | 0.3 | 140 ft |
| Iosco County | 19,100 | 78% | 2.4% | 0.2 | 72 ft |
| Huron County | 19,100 | 63% | 22.7% | 0.0 | 140 ft |
| Leelanau County | 18,700 | 84% | 5.1% | 0.4 | 103 ft |
| Delta County | 18,300 | 53% | 2.6% | 0.1 | 110 ft |
| Cheboygan County | 18,100 | 75% | 1.5% | 0.1 | 115 ft |
| Mason County | 18,000 | 61% | 3.8% | 0.9 | 74 ft |
| Osceola County | 17,800 | 81% | 1.8% | 1.3 | 97 ft |
| Otsego County | 17,500 | 74% | 1.3% | 0.5 | 100 ft |
| Ogemaw County | 17,400 | 88% | 1.7% | 0.3 | 77 ft |
| Chippewa County | 17,400 | 60% | 2.5% | 0.1 | 105 ft |
| Antrim County | 16,000 | 72% | 4.5% | 0.5 | 102 ft |
| Charlevoix County | 15,400 | 58% | 4.5% | 0.5 | 104 ft |
| Kalkaska County | 14,800 | 87% | 1.5% | 0.5 | 83 ft |
| Manistee County | 14,800 | 65% | 4.4% | 0.7 | 91 ft |
| Alpena County | 14,100 | 51% | 1.9% | 0.3 | 82 ft |
| Benzie County | 13,500 | 74% | 5.0% | 0.5 | 95 ft |
| Menominee County | 13,100 | 59% | 1.5% | 0.1 | 66 ft |
| Missaukee County | 13,100 | 87% | 1.7% | 1.2 | 80 ft |
| Houghton County | 12,000 | 37% | 2.2% | 0.1 | 127 ft |
| Arenac County | 11,500 | 74% | 15.3% | 0.1 | 81 ft |
| Crawford County | 10,200 | 84% | 1.8% | 0.4 | 85 ft |
| Lake County | 9,600 | 90% | 1.6% | 0.8 | 68 ft |
| Alcona County | 9,500 | 95% | 2.1% | 0.4 | 75 ft |
| Presque Isle County | 8,600 | 73% | 1.7% | 0.2 | 130 ft |
| Montmorency County | 8,300 | 92% | 1.7% | 0.3 | 76 ft |
| Dickinson County | 7,900 | 35% | 2.2% | 0.1 | 107 ft |
| Oscoda County | 7,700 | 93% | 1.8% | 0.5 | 107 ft |
| Mackinac County | 7,200 | 71% | 2.4% | 0.1 | 95 ft |
| Alger County | 5,900 | 76% | 1.7% | 0.2 | 77 ft |
| Schoolcraft County | 5,000 | 69% | 1.2% | 0.1 | 91 ft |
| Iron County | 4,600 | 49% | 2.4% | 0.1 | 81 ft |
| Gogebic County | 4,600 | 41% | 3.0% | 0.1 | 95 ft |
| Ontonagon County | 3,900 | 67% | 5.4% | 0.1 | 120 ft |
| Baraga County | 3,900 | 61% | 2.3% | 0.1 | 145 ft |
| Luce County | 3,400 | 72% | 1.9% | 0.1 | 82 ft |
| Keweenaw County | 1,100 | 67% | 2.7% | 0.0 | 152 ft |
Shading: red is among the highest counties nationally, amber the middle, green the lower range. Click a column to sort.
Most well users above the arsenic limit
- Tuscola County: about 11,300 people
- Clinton County: about 8,200 people
- Livingston County: about 7,700 people
- Oakland County: about 7,500 people
- Genesee County: about 6,900 people
Test first, then treat what the test finds
We may earn a commission from links below, at no cost to you. Picks follow the testing order, not who pays. How we make money.
1. Certified lab well test
Start here, every year
A mail-in kit analyzed by a certified lab measures bacteria, nitrate, arsenic, metals and more. Test strips cannot measure arsenic or uranium reliably.
Mail-in certified lab well water test
Mid-range2. Sediment pre-filter
Sand, silt or cloudy water
A 5-micron cartridge after the pressure tank catches sand, silt and rust before they reach fixtures or other filters. Cartridges are cheap and swap every few months.
5-micron whole-house sediment filter
Budget3. Iron and sulfur filter
Orange stains or rotten-egg smell
Air-injection or oxidizing-media filters remove orange staining and rotten-egg smell. Size one from a lab result for iron, manganese and hydrogen sulfide.
Air-injection iron and sulfur filter
Premium4. UV disinfection system
Coliform bacteria in a test
Inactivates bacteria and viruses; usually for private wells or after boil notices.
12 GPM whole-house UV purifier
Premium5. Under-sink reverse osmosis
Arsenic, nitrate or uranium in a test
The most thorough option for drinking water: PFAS, lead, nitrate, arsenic and more. Look for NSF/ANSI 58.
Waterdrop G3P600 tankless RO
Price at Waterdrop, checked Oct 5, 2026or compare on Amazon
iSpring RCC7AK reverse osmosis
Mid-range6. Whole-house well filter
Several problems at once
Multi-stage sediment and carbon for every tap. Add UV if bacteria shows up, and choose stages from your lab results, not a guess.
Waterdrop WHF21 2-stage whole-house filter
Mid-rangeQuestions
Which Michigan counties rely most on wells?+
By share of homes: Alcona County (95%), Oscoda County (93%), Montmorency County (92%), Lake County (90%), Roscommon County (89%). By number of people: Oakland County (260,100), Genesee County (176,600), Kent County (165,700).
Is arsenic a problem in Michigan wells?+
USGS estimates about 192,700 Michigan well users have water above the 10 microgram per liter arsenic limit that applies to public systems, the largest numbers in Tuscola County, Clinton County, Livingston County. Arsenic has no taste or smell, so only a lab test finds it.
Do I have to test my well when I sell a house in Michigan?+
We could not confirm a statewide rule for Michigan. Check with your county health department. Buyers can still make a lab test a condition of the offer.
How often should I test my well?+
No federal law covers private wells. EPA's drinking water limits apply to public water systems, so testing and treating a private well is up to the owner. EPA and CDC recommend testing at least once a year for coliform bacteria, nitrate, pH and total dissolved solids, and testing for arsenic, uranium, radon and other local concerns based on where you live.
Well-user counts, arsenic and nitrate figures are each a modeled estimate built from national datasets, not a count of tested wells, and well depths summarize drilling records rather than every well. Your own well can be very different from the county average, which is why the only answer for your home is a lab test. Sources: EPA Office of Research and Development, Water Source 2020 (private well estimates by census block); CDC Environmental Public Health Tracking, Well Water Index (from USGS nitrate and arsenic models); USGS, county-level domestic well population with arsenic above 10 micrograms per liter (Ayotte and others, 2017); USGS Synthesized Domestic Well Database for the Conterminous United States (SynDWell-US), McCarthy and others, 2025 (depth, where a county has 30+ usable records).