Michigan Private Well Water Risk: Arsenic & Nitrate
These figures are USGS statistical estimates for private (domestic) wells in Michigan. They describe the area's modeled risk — not any single well.
This is a modeled probability for the area, not a measurement of your well. USGS statistical models estimate how many private wells in this area are likely to exceed the federal limit — they cannot tell you what is in your water. Two neighbors can have very different results. The only way to know your well is to test it.
Nitrate
0%
of the private-well population is modeled above the 10 mg/L nitrate limit
~530
people on wells estimated above the limit
~2,440,000
total residents on private wells statewide
Source: USGS machine-learning nitrate model, Ransom et al. (2022), domestic-well depth zone.
Arsenic
Across Michigan, an estimated ~192,748 people rely on private wells with modeled arsenic above the 10 µg/L EPA limit. The highest modeled exposure is in Tuscola County (~11,252 people).
Counties with the highest modeled arsenic exposure
| County | Est. well residents over arsenic limit | 90% range |
|---|---|---|
| Tuscola County | ~11,252 | 9,269–13,487 |
| Clinton County | ~8,229 | 6,935–9,738 |
| Livingston County | ~7,681 | 6,123–9,693 |
| Oakland County | ~7,540 | 6,002–9,534 |
| Genesee County | ~6,942 | 5,661–8,501 |
| Lenawee County | ~6,064 | 4,522–7,996 |
| Sanilac County | ~5,945 | 4,889–7,143 |
| Gratiot County | ~5,767 | 4,736–6,962 |
| Midland County | ~5,663 | 4,666–6,846 |
| Lapeer County | ~5,544 | 4,626–6,637 |
| Kent County | ~5,442 | 4,440–6,746 |
| Monroe County | ~5,370 | 4,071–7,667 |
| Washtenaw County | ~5,310 | 3,937–7,157 |
| Eaton County | ~5,128 | 4,365–6,075 |
| Saginaw County | ~4,397 | 3,683–5,148 |
| Shiawassee County | ~4,393 | 3,657–5,254 |
| Huron County | ~3,924 | 3,251–4,690 |
| St. Clair County | ~3,797 | 2,861–4,999 |
| Grand Traverse County | ~3,678 | 2,309–5,654 |
| Allegan County | ~3,677 | 2,897–4,670 |
| Jackson County | ~3,418 | 2,770–4,236 |
| Bay County | ~3,183 | 2,629–3,752 |
| Isabella County | ~3,180 | 2,627–3,833 |
| Ottawa County | ~3,052 | 2,387–3,884 |
| Muskegon County | ~3,036 | 2,356–3,917 |
| Calhoun County | ~2,743 | 2,167–3,476 |
| Montcalm County | ~2,338 | 1,877–2,908 |
| Roscommon County | ~2,032 | 1,394–2,904 |
| Van Buren County | ~2,016 | 1,558–2,615 |
| Gladwin County | ~1,980 | 1,588–2,472 |
| Ingham County | ~1,922 | 1,585–2,329 |
| Alpena County | ~1,899 | 1,325–2,622 |
| Leelanau County | ~1,846 | 1,150–2,857 |
| Branch County | ~1,773 | 1,404–2,232 |
| Hillsdale County | ~1,766 | 1,435–2,180 |
| Benzie County | ~1,766 | 1,109–2,677 |
| Barry County | ~1,748 | 1,376–2,246 |
| Newaygo County | ~1,710 | 1,317–2,237 |
| Berrien County | ~1,648 | 1,219–2,244 |
| Delta County | ~1,635 | 1,324–2,039 |
| Ionia County | ~1,488 | 1,212–1,833 |
| Antrim County | ~1,413 | 894–2,154 |
| Cass County | ~1,402 | 1,051–1,868 |
| Charlevoix County | ~1,371 | 878–2,073 |
| Cheboygan County | ~1,341 | 968–1,875 |
| Manistee County | ~1,307 | 848–1,956 |
| Mecosta County | ~1,212 | 932–1,588 |
| Macomb County | ~1,201 | 908–1,585 |
| Mason County | ~1,200 | 867–1,644 |
| Marquette County | ~1,198 | 934–1,541 |
| Oceana County | ~1,094 | 827–1,438 |
| Menominee County | ~1,079 | 886–1,311 |
| Emmet County | ~1,072 | 741–1,534 |
| Arenac County | ~1,057 | 882–1,315 |
| Kalamazoo County | ~1,033 | 784–1,372 |
| St. Joseph County | ~928 | 697–1,245 |
| Clare County | ~915 | 689–1,222 |
| Ogemaw County | ~876 | 686–1,121 |
| Otsego County | ~866 | 570–1,304 |
| Chippewa County | ~860 | 659–1,123 |
| Wexford County | ~842 | 602–1,202 |
| Alcona County | ~821 | 567–1,168 |
| Missaukee County | ~727 | 533–986 |
| Kalkaska County | ~681 | 488–956 |
| Osceola County | ~666 | 507–878 |
| Montmorency County | ~591 | 403–862 |
| Presque Isle County | ~591 | 449–771 |
| Iosco County | ~520 | 401–669 |
| Mackinac County | ~497 | 378–672 |
| Crawford County | ~458 | 327–644 |
| Dickinson County | ~443 | 368–533 |
| Houghton County | ~426 | 339–531 |
| Lake County | ~363 | 265–502 |
| Schoolcraft County | ~355 | 272–463 |
| Luce County | ~335 | 253–439 |
| Oscoda County | ~326 | 239–444 |
| Alger County | ~320 | 249–413 |
| Baraga County | ~283 | 229–350 |
| Ontonagon County | ~129 | 108–155 |
3 additional Michigan counties have lower modeled arsenic exposure (fewer than 100 estimated well residents over the limit).
Source: USGS domestic-well arsenic model, Lombard et al. (2021); county population product (2017).
Treating arsenic in Michigan
Arsenic is not removed by carbon pitchers or faucet filters. Reverse osmosis is the treatment that brings it below the federal limit at your tap.
We may earn a commission from Amazon at no extra cost to you.