Private wells
North Dakota well water: who's on a well and what to test for
People on private wells
152,600
Homes on wells
19.3%
Est. above arsenic limit
2,000
Every North Dakota 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.
| Burleigh County | 10,500 | 9% | 9.1% | 0.3 | 130 ft |
| Ward County | 8,300 | 10% | 6.9% | 0.1 | 206 ft |
| Rolette County | 7,000 | 55% | 5.9% | 0.1 | n/a |
| Cass County | 6,800 | 3% | 13.4% | 0.0 | 177 ft |
| Grand Forks County | 6,700 | 8% | 7.4% | 0.5 | n/a |
| Williams County | 5,900 | 14% | 7.1% | 0.3 | 95 ft |
| McKenzie County | 5,900 | 35% | 4.4% | 0.2 | 105 ft |
| Morton County | 5,900 | 17% | 5.0% | 0.3 | 280 ft |
| McLean County | 5,300 | 54% | 5.1% | 0.1 | 126 ft |
| Richland County | 5,100 | 29% | 7.8% | 0.1 | 126 ft |
| Stark County | 4,900 | 13% | 5.5% | 0.8 | 120 ft |
| Stutsman County | 4,400 | 20% | 6.3% | 0.2 | 106 ft |
| Benson County | 4,200 | 69% | 10.0% | 0.1 | 98 ft |
| Ramsey County | 4,000 | 33% | 8.6% | 0.0 | 100 ft |
| Walsh County | 3,300 | 32% | 5.2% | 0.2 | n/a |
| Barnes County | 3,200 | 30% | 6.6% | 0.3 | 75 ft |
| Pembina County | 3,200 | 46% | 6.1% | 0.2 | n/a |
| Mountrail County | 3,200 | 32% | 6.7% | 0.1 | 142 ft |
| Cavalier County | 3,100 | 83% | 3.6% | 0.1 | 90 ft |
| Bottineau County | 3,100 | 52% | 5.1% | 0.0 | 74 ft |
| McHenry County | 3,000 | 54% | 9.0% | 0.1 | 80 ft |
| Dunn County | 2,800 | 64% | 4.5% | 0.5 | 76 ft |
| Sioux County | 2,800 | 74% | 6.8% | 0.2 | 220 ft |
| Traill County | 2,700 | 30% | 12.3% | 0.1 | 155 ft |
| LaMoure County | 2,400 | 52% | 5.9% | 0.1 | 92 ft |
| Ransom County | 2,300 | 37% | 4.8% | 0.4 | 61 ft |
| Mercer County | 2,200 | 29% | 4.6% | 0.5 | 150 ft |
| Dickey County | 1,800 | 36% | 10.0% | 0.2 | 97 ft |
| Divide County | 1,600 | 72% | 8.0% | 0.3 | 120 ft |
| Pierce County | 1,600 | 33% | 6.8% | 0.1 | n/a |
| Sargent County | 1,600 | 38% | 8.0% | 0.1 | 148 ft |
| Emmons County | 1,500 | 47% | 7.6% | 1.0 | 108 ft |
| Wells County | 1,500 | 34% | 5.7% | 0.1 | 90 ft |
| Grant County | 1,500 | 65% | 5.3% | 0.6 | n/a |
| Kidder County | 1,500 | 66% | 8.1% | 0.3 | 150 ft |
| Steele County | 1,300 | 63% | 8.1% | 0.4 | 45 ft |
| Oliver County | 1,300 | 66% | 4.1% | 0.7 | n/a |
| Foster County | 1,200 | 38% | 5.5% | 0.1 | 108 ft |
| Burke County | 1,200 | 48% | 6.8% | 0.1 | 165 ft |
| Nelson County | 1,200 | 36% | 5.0% | 0.1 | 82 ft |
| Griggs County | 1,100 | 51% | 5.4% | 0.4 | 80 ft |
| Bowman County | 1,100 | 33% | 4.8% | 0.7 | 220 ft |
| Hettinger County | 1,000 | 38% | 5.7% | 0.9 | 161 ft |
| Adams County | 980 | 36% | 5.7% | 0.5 | 160 ft |
| Renville County | 970 | 43% | 6.9% | 0.0 | n/a |
| Towner County | 940 | 42% | 7.1% | 0.0 | 150 ft |
| McIntosh County | 900 | 32% | 6.5% | 0.6 | 50 ft |
| Logan County | 890 | 46% | 4.4% | 0.3 | 130 ft |
| Sheridan County | 820 | 57% | 6.4% | 0.0 | 260 ft |
| Eddy County | 810 | 31% | 4.5% | 0.2 | 67 ft |
| Billings County | 810 | 79% | 6.6% | 0.3 | 48 ft |
| Golden Valley County | 690 | 33% | 4.1% | 0.3 | n/a |
| Slope County | 600 | 81% | 4.9% | 0.3 | n/a |
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
- Burleigh County: about 360 people
- Ward County: about 160 people
- Cass County: about 120 people
- McKenzie County: about 120 people
- Morton County: about 110 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 North Dakota counties rely most on wells?+
By share of homes: Cavalier County (83%), Slope County (81%), Billings County (79%), Sioux County (74%), Divide County (72%). By number of people: Burleigh County (10,500), Ward County (8,300), Rolette County (7,000).
Is arsenic a problem in North Dakota wells?+
USGS estimates about 2,000 North Dakota well users have water above the 10 microgram per liter arsenic limit that applies to public systems, the largest numbers in Burleigh County, Ward County, Cass 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 North Dakota?+
We could not confirm a statewide rule for North Dakota. 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).