Private wells
Minnesota well water: who's on a well and what to test for
People on private wells
1,279,300
Homes on wells
24.5%
Est. above arsenic limit
80,400
Every Minnesota 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.
| Anoka County | 85,300 | 22% | 2.3% | 0.3 | 136 ft |
| St. Louis County | 62,500 | 35% | 3.5% | 0.0 | 107 ft |
| Hennepin County | 62,200 | 4% | 6.4% | 0.2 | 154 ft |
| Washington County | 54,200 | 21% | 2.9% | 0.6 | 180 ft |
| Sherburne County | 49,000 | 48% | 4.7% | 1.1 | 91 ft |
| Wright County | 44,700 | 33% | 7.0% | 0.6 | 112 ft |
| Stearns County | 41,100 | 27% | 7.5% | 1.7 | 75 ft |
| Dakota County | 39,900 | 9% | 3.3% | 0.3 | 260 ft |
| Otter Tail County | 36,900 | 69% | 14.7% | 0.4 | 92 ft |
| Crow Wing County | 34,600 | 62% | 2.1% | 0.2 | 71 ft |
| Chisago County | 31,300 | 55% | 2.9% | 0.3 | 131 ft |
| Ramsey County | 28,500 | 5% | 3.5% | 0.5 | 150 ft |
| Itasca County | 27,100 | 65% | 5.8% | 0.2 | 85 ft |
| Cass County | 25,500 | 89% | 2.9% | 0.2 | 69 ft |
| Scott County | 25,100 | 17% | 8.5% | 0.1 | 220 ft |
| Beltrami County | 24,100 | 53% | 3.6% | 0.2 | 84 ft |
| Isanti County | 23,900 | 58% | 3.7% | 0.3 | 110 ft |
| Douglas County | 23,300 | 61% | 10.0% | 0.5 | 99 ft |
| Olmsted County | 23,000 | 13% | 3.0% | 0.3 | 310 ft |
| Becker County | 22,200 | 66% | 11.4% | 0.1 | 90 ft |
| Morrison County | 21,400 | 63% | 4.8% | 1.4 | 70 ft |
| Carlton County | 20,300 | 56% | 3.6% | 0.1 | 100 ft |
| Pine County | 18,800 | 69% | 5.8% | 0.1 | 91 ft |
| Todd County | 17,000 | 69% | 6.1% | 1.3 | 84 ft |
| Carver County | 16,500 | 15% | 23.0% | 0.1 | 197 ft |
| Hubbard County | 16,400 | 80% | 3.3% | 0.5 | 70 ft |
| Kandiyohi County | 16,400 | 42% | 38.2% | 0.1 | 107 ft |
| Rice County | 16,300 | 25% | 13.0% | 0.1 | 220 ft |
| Goodhue County | 15,600 | 30% | 3.6% | 0.2 | 320 ft |
| Mille Lacs County | 14,500 | 54% | 5.6% | 0.3 | 72 ft |
| Winona County | 14,000 | 27% | 3.2% | 0.2 | 175 ft |
| Benton County | 13,400 | 30% | 7.9% | 0.8 | 75 ft |
| Meeker County | 12,700 | 55% | 44.3% | 0.1 | 120 ft |
| Aitkin County | 12,600 | 87% | 2.9% | 0.1 | 91 ft |
| Blue Earth County | 12,400 | 18% | 26.8% | 0.0 | 174 ft |
| Kanabec County | 12,100 | 77% | 5.2% | 0.3 | 90 ft |
| Le Sueur County | 10,900 | 39% | 26.9% | 0.1 | 235 ft |
| Polk County | 10,700 | 38% | 31.2% | 0.1 | 120 ft |
| McLeod County | 10,000 | 26% | 28.1% | 0.0 | 143 ft |
| Fillmore County | 9,400 | 42% | 4.6% | 0.5 | 321 ft |
| Mower County | 8,800 | 21% | 6.1% | 0.0 | 160 ft |
| Clay County | 8,500 | 13% | 17.5% | 0.1 | 137 ft |
| Roseau County | 8,500 | 53% | 2.6% | 0.0 | 90 ft |
| Freeborn County | 8,300 | 25% | 8.8% | 0.0 | 187 ft |
| Wabasha County | 7,800 | 37% | 3.7% | 0.4 | 184 ft |
| Houston County | 7,800 | 40% | 3.5% | 0.3 | 160 ft |
| Wadena County | 7,500 | 53% | 5.0% | 0.4 | 72 ft |
| Dodge County | 6,700 | 32% | 8.1% | 0.1 | 224 ft |
| Steele County | 6,600 | 17% | 13.0% | 0.1 | 186 ft |
| Pope County | 6,500 | 60% | 8.1% | 0.4 | 105 ft |
| Nicollet County | 6,400 | 19% | 18.7% | 0.0 | 248 ft |
| Sibley County | 6,400 | 41% | 27.0% | 0.0 | 226 ft |
| Clearwater County | 6,400 | 73% | 7.3% | 0.1 | 101 ft |
| Waseca County | 5,900 | 31% | 15.4% | 0.0 | 210 ft |
| Brown County | 5,700 | 21% | 31.8% | 0.0 | 147 ft |
| Renville County | 5,400 | 36% | 32.7% | 0.0 | 155 ft |
| Redwood County | 5,200 | 32% | 39.6% | 0.1 | 111 ft |
| Marshall County | 5,100 | 56% | 5.0% | 0.0 | 149 ft |
| Pennington County | 5,100 | 32% | 5.7% | 0.0 | 183 ft |
| Martin County | 5,100 | 24% | 43.1% | 0.0 | 165 ft |
| Nobles County | 5,000 | 25% | 7.7% | 0.3 | 150 ft |
| Lyon County | 4,900 | 18% | 11.6% | 0.1 | 139 ft |
| Lake County | 4,900 | 54% | 2.6% | 0.0 | 205 ft |
| Faribault County | 4,700 | 32% | 23.4% | 0.0 | 140 ft |
| Yellow Medicine County | 4,100 | 40% | 18.2% | 0.2 | 115 ft |
| Jackson County | 4,100 | 40% | 40.6% | 0.0 | 242 ft |
| Chippewa County | 4,100 | 31% | 7.4% | 0.2 | 121 ft |
| Koochiching County | 4,000 | 39% | 4.4% | 0.0 | 125 ft |
| Swift County | 3,800 | 37% | 21.1% | 0.1 | 109 ft |
| Murray County | 3,600 | 47% | 17.5% | 0.1 | 151 ft |
| Cook County | 3,500 | 64% | 2.4% | 0.1 | 205 ft |
| Lac qui Parle County | 3,400 | 48% | 18.3% | 0.1 | 136 ft |
| Stevens County | 3,400 | 32% | 5.1% | 0.2 | 126 ft |
| Cottonwood County | 3,300 | 28% | 31.9% | 0.0 | 153 ft |
| Grant County | 3,200 | 55% | 16.1% | 0.1 | 110 ft |
| Mahnomen County | 3,100 | 61% | 8.8% | 0.0 | 107 ft |
| Rock County | 3,100 | 30% | 21.3% | 0.6 | 190 ft |
| Watonwan County | 2,900 | 28% | 40.4% | 0.0 | 137 ft |
| Pipestone County | 2,800 | 26% | 5.4% | 0.5 | 119 ft |
| Lake of the Woods County | 2,800 | 77% | 3.7% | 0.0 | 95 ft |
| Kittson County | 2,700 | 61% | 5.6% | 0.1 | 80 ft |
| Norman County | 2,500 | 39% | 8.9% | 0.1 | 164 ft |
| Lincoln County | 2,400 | 38% | 4.5% | 0.2 | 150 ft |
| Wilkin County | 2,300 | 32% | 11.3% | 0.1 | 144 ft |
| Red Lake County | 2,000 | 48% | 5.6% | 0.0 | 139 ft |
| Big Stone County | 2,000 | 39% | 23.9% | 0.3 | 174 ft |
| Traverse County | 1,200 | 40% | 9.1% | 0.0 | 137 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
- Blue Earth County: about 4,300 people
- St. Louis County: about 3,600 people
- Anoka County: about 3,000 people
- Crow Wing County: about 2,700 people
- Nicollet County: about 2,200 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 Minnesota counties rely most on wells?+
By share of homes: Cass County (89%), Aitkin County (87%), Hubbard County (80%), Lake of the Woods County (77%), Kanabec County (77%). By number of people: Anoka County (85,300), St. Louis County (62,500), Hennepin County (62,200).
Is arsenic a problem in Minnesota wells?+
USGS estimates about 80,400 Minnesota well users have water above the 10 microgram per liter arsenic limit that applies to public systems, the largest numbers in Blue Earth County, St. Louis County, Anoka 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 Minnesota?+
We could not confirm a statewide rule for Minnesota. 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).