North Dakota Private Well Water Quality 2026

Arsenic in North Dakota Well Water

Arsenic is North Dakota’s most widespread well water concern. It occurs naturally in the state’s groundwater due to the geology of the Northern Plains — felsic volcanic rocks and glacial deposits that release arsenic into aquifers over time. The North Dakota Department of Environmental Quality (NDDEQ) acknowledges that arsenic concentrations vary throughout the state and can exceed the EPA maximum contaminant level (MCL) of 10 µg/L (10 parts per billion).

Research conducted as part of the Strong Heart Water Study — a peer-reviewed intervention trial published in Environmental Science & Technology — found that 26.1% of private wells tested in tribal communities in North Dakota and South Dakota exceeded the EPA arsenic MCL of 10 µg/L, with concentrations ranging as high as 198 µg/L. This research specifically examined American Indian reservation communities where naturally occurring arsenic is particularly elevated, but it illustrates the scale of geological arsenic risk across the Northern Plains. Eastern North Dakota, including Cass County, has documented elevated arsenic in well water serving rural households.

Arsenic is colourless and tasteless — there is no way to detect it without laboratory testing. Long-term exposure is linked to bladder, lung, and skin cancers, cardiovascular disease, and nerve damage. NDDEQ recommends all private well owners test for arsenic, and it should be considered a priority test regardless of where in North Dakota you live.

Nitrate Contamination — The Agricultural Risk

North Dakota is one of the most intensively farmed states in the US, and nitrate contamination from agricultural fertiliser runoff is a significant risk for private wells across the state — particularly in the Red River Valley and other eastern agricultural regions. Livestock operations, feedlots, and septic systems also contribute to nitrate levels in shallow groundwater.

The EPA MCL for nitrate is 10 mg/L. Levels above this threshold are dangerous for infants under six months, potentially causing methemoglobinemia — “blue baby syndrome” — a potentially fatal condition in which the blood’s ability to carry oxygen is reduced. Adults with certain health conditions may also be at risk. If you have an infant in the household, your well should be tested for nitrate before giving the water to a child.

Nitrate risk is higher in shallow wells and in areas close to crop fields, livestock operations, or septic systems. Deeper wells provide some protection but are not immune — nitrate has been documented at varying depths in North Dakota’s agricultural counties.

The Bakken Oil Factor — Selenium, Radium and Produced Water Spills

Western North Dakota sits atop the Bakken Formation — one of the most productive shale oil regions in the US. Oil and gas production generates large volumes of “produced water” or brine — highly saline wastewater that comes up alongside oil and contains a range of toxic contaminants. Records from the North Dakota Department of Health (now the DEQ) document more than 4,000 accidental produced water spills in the state since 2001.

Research from Duke University, published in Environmental Science & Technology, found that spill sites in the Bakken region contained elevated concentrations of selenium, lead, ammonium, and radioactive radium. Selenium at some spill sites was found at levels far exceeding EPA freshwater aquatic life guidelines; radium accumulated in soils at spill sites and was still detectable four years after the events. The researchers noted that contamination from brine spills is “remarkably persistent in the environment.” These contaminants can migrate into surface water and, over time, into groundwater.

A separate USGS study of the Bakken region found no widespread hydrocarbon contamination in drinking water aquifers at the time of sampling, but noted some evidence of minor contamination near oil wells. The slow movement of groundwater in the region means potential long-term impacts may take years to become detectable. Well owners in Bakken-producing counties — McKenzie, Williams, Mountrail, Dunn, and Burke — should be aware of this risk and consider testing for selenium, radium, and volatile organic compounds, particularly if their well is located near oil infrastructure.

North Dakota also has naturally occurring selenium in its geology, particularly in western and central regions, where it can leach into groundwater independently of oil activity. Selenium is essential in very small amounts but toxic at elevated concentrations, and has no detectable taste or smell.

PFAS in North Dakota — Military Sites and Limited Testing

PFAS has been confirmed in soil and groundwater at multiple North Dakota military sites. According to the NDDEQ, the Air National Guard base near Fargo’s Hector International Airport, Minot Air Force Base, and Grand Forks Air Force Base all have “elevated” PFAS levels in groundwater, primarily from the use of AFFF firefighting foam. Environmental Working Group data drawn from Department of Defense records found PFOA and PFOS concentrations in groundwater at Minot AFB at extremely high levels.

A 2018 NDDEQ statewide study of public drinking water found PFAS detections in several systems — including Fargo, Bismarck, Grand Forks, and Minot — but at levels below the 70 ppt health advisory that was then in effect. With the EPA’s 2024 MCL of 4 ppt for PFOA and PFOS now in force for public systems, some of those earlier detections may merit re-evaluation. No public water systems in North Dakota are currently known to be out of compliance with the new federal limits, but ongoing monitoring is in progress.

As of early 2024, the NDDEQ stated it was not aware of any private wells in the state testing positive for PFAS. However, private well testing near military sites has been limited. Well owners within a few miles of any Air Force base, National Guard installation, airport, or fire training area should treat PFAS as a precautionary test — contamination from military sites can migrate through groundwater over years without any visible sign.

Coliform bacteria is a consistent risk in any private well, particularly those with ageing casing, improper sealing, or proximity to septic systems or livestock operations. Annual testing for bacteria is a minimum standard for any well owner in North Dakota.

Regulatory Situation for North Dakota Well Owners

Private residential wells in North Dakota are not regulated under state or federal drinking water law. The Safe Drinking Water Act covers public water systems — wells serving at least 25 people or 15 connections — but not private household wells. The NDDEQ has no authority to mandate testing or impose standards on private wells. Testing, treatment, and maintenance are entirely the well owner’s responsibility.

North Dakota has no state-level PFAS MCLs of its own. The federal 4 ppt standard for PFOA and PFOS, finalised in 2024, applies only to public water systems, not private wells. The state has not adopted any supplementary protections for private well owners beyond general guidance on testing.

Check our North Dakota municipal water quality page for city-by-city tap water data including Fargo, or visit our Fargo water quality page for detailed local data. Use our live boil water notice tracker for active advisories across the state.

Higher-Risk Areas and Situations in North Dakota

Location and land use significantly affect which contaminants pose the greatest risk to your well.

How to Test Your North Dakota Well Water — and What to Do Next

Every private well owner in North Dakota should test their water — at minimum for bacteria and nitrate annually, and for arsenic and selenium at least once. If your well is in an agricultural area, nitrate testing every year is non-negotiable. If you are in western North Dakota near oil infrastructure, add selenium, radium, and VOCs to your panel. If you are near any military installation or airport, add a PFAS panel.

Contact your local county health department or the NDDEQ (deq.nd.gov) for a certified laboratory list. The NDDEQ Arsenic in Drinking Water fact sheet — available on their website — provides specific guidance for well owners on understanding test results and selecting treatment. For PFAS near military sites, the NDDEQ is the primary point of contact.

For filter options, our well water filter guide covers reverse osmosis systems for arsenic, nitrate, selenium, and PFAS; UV disinfection for bacteria; and whole-house well systems for comprehensive treatment. You can also browse our full water filter solutions page or check your ZIP code for local water quality context.

For neighbouring well water data, see our Michigan private well water page — or return to the private well water directory to find your state.