By the Closer Look Inspectors team · Facts checked October 8, 2026 against MDH, MPCA and EPA sources · About our inspectors
Arsenic occurs naturally in Minnesota rocks and soil and dissolves into groundwater. MDH reports about 10 percent of private wells exceed 10 µg/L, and levels can differ between neighboring wells. MDH recommends every well be tested for arsenic at least once. Water above the standard should be treated or replaced with another source.
All the water tests we offer
Bacteria
Shows whether surface water or waste is reaching the well.
- Surface contamination reaching the wellNone should be present (MDH)
- Fecal contamination from septic, manure or wildlifeNone should be present (MDH)
Health chemicals
No taste, color or smell. These are the long-term health checks.
- Fertilizer, septic and manure; highest risk to infants10 mg/L (EPA)
- Natural arsenic from Minnesota rock and soil10 µg/L (EPA)
- Lead service lines, solder and brass fixturesNo safe level (MDH)
- ManganeseNatural manganese; a concern for infants100 µg/L for infants (MDH guidance)
- FluorideNatural fluoride; dental health4.0 mg/L (EPA)
- UraniumNatural radionuclide in groundwater30 µg/L (EPA)
Petroleum & solvents
Fuel and chemical spills from old tanks or nearby sites.
Household quality
Staining, scale and taste, and choosing the right treatment.
- IronRusty staining and metallic taste0.3 mg/L, aesthetic (MDH)
- HardnessScale buildup; sizing a water softenerNo health standard
- pHCorrosive or scaling water6.5 to 8.5, aesthetic (EPA)
- SulfateTaste and odor; diarrhea risk for infants250 mg/L, aesthetic (EPA)
Limits from MDH, EPA and MPCA. Your lab report compares each result to these values.
Health standard: 10 µg/L (10 ppb), EPA standard; EPA's health goal is 0 µg/L. MDH enforces it for public systems.
Where arsenic comes from in Minnesota
Arsenic occurs naturally in Minnesota rocks and soil and can dissolve into groundwater, and glacial movement affects where it is found. Some comes from human activity, since arsenic was once used in pesticides and as a wood preservative. MDH reports that about 10 percent of private wells in Minnesota exceed 10 µg/L, some reach 350 µg/L, and arsenic was detected in about 40 percent of new wells drilled since 2008. Levels can differ between neighboring wells, so one well may be high while the one next door is not. Few public water systems have exceeded the EPA standard.
Health effects and who is most at risk
Long-term exposure to arsenic in drinking water is linked to diabetes and to cancers of the bladder, lungs, liver, and other organs. Other effects include cardiovascular and respiratory disease, reduced intelligence in children, and skin problems such as lesions, discoloration, and corns. Health effects may take many years to appear, and levels below the standard can still raise cancer risk over time. The EPA standard is 10 µg/L (10 parts per billion) and its health goal is 0. MDH says that because skin does not easily absorb arsenic, water is considered safe for washing and bathing unless levels exceed 500 µg/L.
Signs and when to test
Arsenic in water has no taste, color, or smell that warns you, so testing is the only way to know. MDH recommends testing every private well for arsenic at least once, using an accredited laboratory. Wells built since August 2008 were tested by well contractors, and results may be on the Minnesota Well Index. If arsenic is detected in a new well, MDH advises retesting about six months after construction, because levels can rise or fall early on. If it is not detected in the first sample, it is unlikely to appear later. A home purchase is a practical time to confirm the result.
If your result is high: treatment options
MDH highly recommends taking action if arsenic is above 10 µg/L. Options include using an alternate water source or installing a treatment system. MDH lists reverse osmosis, distillation, anion exchange, adsorptive media, and several oxidation-and-filtration approaches. It notes that conventional water softeners and activated carbon filters alone do not remove arsenic, and that boiling concentrates it. Choose units certified by NSF International, UL, or the Water Quality Association, and use a licensed installer unless you own and occupy the home. Other alternatives include a new well in a different formation or connecting to a public water system. Retest after treatment.
Facts checked October 2026 against: Minnesota Department of Health, Minnesota Department of Health, Minnesota Department of Health, Minnesota Department of Health.
Arsenic water testing in pictures
Minnesota private well testing timeline
| Test | Year 1 | Year 2 | Year 3 | Year 4 | Year 5 | Year 6 |
|---|---|---|---|---|---|---|
| Coliform bacteria | ||||||
| Nitrate | ||||||
| Arsenic | ||||||
| Lead |
Test again any time after flooding, after work on the well, or when the water's taste, color or smell changes, and always when you buy a home with a well.
Arsenic in Minnesota private wells, out of every 100
About 40 in 100 have some arsenic About 10 in 100 are above the 10 µg/L standard
You can't see, smell or taste arsenic. One lab test tells you where the well stands. Get a free instant quote
How deep Minnesota wells go
Depth and aquifer change what is in the water. Test the well you are buying, not the neighbor's. Get a free instant quote
Quick answers
How common is arsenic in Minnesota well water?
MDH reports about 10 percent of private wells in Minnesota have arsenic above the 10 µg/L standard, and arsenic was detected in about 40 percent of new wells drilled since 2008. Some wells have reached 350 µg/L. Levels vary between wells, even close together, so each well needs its own test.
What is the safe level of arsenic in drinking water?
The EPA standard is 10 µg/L, equal to 10 parts per billion, though the EPA health goal is 0. MDH highly recommends taking action if a private well is above 10 µg/L, and notes that levels below the standard can still increase cancer risk over many years.
How often should I test my well for arsenic?
MDH recommends testing every private well for arsenic at least once. If arsenic is not detected in the first sample, it is unlikely to appear later. If it is detected in a new well, MDH recommends retesting about six months after construction. Use an accredited laboratory.
How do you remove arsenic from well water?
MDH lists reverse osmosis, distillation, anion exchange, and adsorptive media, plus oxidation or chlorination followed by filtration. Water softeners and activated carbon alone do not remove arsenic, and boiling concentrates it. Choose a unit certified by NSF International, UL, or WQA, and retest the water after installation.
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