By the Closer Look Inspectors team · Facts checked October 8, 2026 against MDH, MPCA and EPA sources · About our inspectors
Nitrate comes from fertilizer, septic and sewage discharge, animal waste, and natural plant decay. It matters most for infants: bottle-fed babies under six months face the highest risk of blue baby syndrome. MDH reports some Minnesota township testing found over 10 percent of sampled private wells above 10 mg/L, and recommends testing before a newborn drinks the water.
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 mg/L (as nitrogen), EPA standard; MDH treats levels above 10 mg/L in a private well as harmful.
Where nitrate comes from in Minnesota
Nitrate occurs naturally, and natural processes usually keep drinking water below 3 mg/L. Human sources include fertilizer on yards, gardens, golf courses, and crops, plus septic systems, sewage, animal manure, feedlots, landfills, and urban drainage. About 4 percent of private wells built since 1991 have nitrate above 3 mg/L, and the Minnesota Department of Agriculture's Township Testing Program found more than 10 percent of sampled private wells above 10 mg/L in some townships in several parts of the state. Shallow wells, wells in sand or fractured rock aquifers, older wells, and wells with damaged casings face higher risk.
Health effects and who is most at risk
Too much nitrate can cause methemoglobinemia, or blue baby syndrome, which reduces how well blood carries oxygen. Bottle-fed babies under six months old are at the highest risk, and the condition can cause serious illness or death. Lips and skin may turn bluish, though this can be hard to see in infants. People with G6PD deficiency or certain metabolic conditions may also be at higher risk. The EPA standard is 10 mg/L as nitrogen. Research is ongoing into possible links at lower levels with thyroid problems, pregnancy outcomes, and colorectal cancer, but findings are not confirmed.
Signs and when to test
You cannot taste, see, or smell nitrate, so only a laboratory test shows your level. MDH recommends regular nitrate testing of private wells at an accredited laboratory, and testing when planning a pregnancy or before infants will use the water. A result above 1 mg/L suggests more testing may be wise. Wells at higher risk include shallow wells, dug wells with casings that are not watertight, wells built before 1974, and wells near septic systems or in agricultural areas. A home purchase is a sensible time for a baseline result.
If your result is high: treatment options
Above 10 mg/L, MDH says to use a safe alternative such as bottled water, especially for formula for infants under six months. Do not boil the water, because boiling concentrates nitrate. Have a licensed well contractor inspect the well and find and remove nitrate sources on the property. Home treatment is an option only after that. MDH's home treatment guidance lists anion exchange resins, reverse osmosis, and distillation among units that may address nitrate, and advises choosing a unit certified by NSF, UL, or WQA. Babies under six months should still not drink treated well water.
Facts checked October 2026 against: Minnesota Department of Health, Minnesota Department of Health, Minnesota Department of Health, Minnesota Department of Health, Minnesota Department of Health.
Nitrate 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.
How far a well must be from common hazards in Minnesota
- Building (closest projection)3 ft
- Lake, river, stream or pond35 ft
- Septic tank50 ft
- Drainfield (soil dispersal area)50 ft (100 ft sensitive well)
- Animal feedlot or building (over 1 animal unit)50 ft
- Cesspool or seepage pit75 ft (150 ft sensitive well)
- Unroofed feedlot, 300+ animal units100 ft
- Unprotected petroleum tank, 1,100+ gallons150 ft
Septic, feedlot or fuel tank near the well? A coliform and nitrate test shows whether it is reaching the water. 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
Is nitrate in well water dangerous for babies?
Yes, it can be. Nitrate can cause methemoglobinemia, or blue baby syndrome, which reduces how well blood carries oxygen. Bottle-fed babies under six months are at highest risk. If nitrate is above 10 mg/L, MDH says to use bottled water or another safe source for infant formula.
What is the safe level of nitrate in drinking water in Minnesota?
The EPA standard is 10 mg/L of nitrate measured as nitrogen, equal to 10 parts per million. It is based on protecting infants from blue baby syndrome. Natural processes usually keep drinking water below 3 mg/L, so higher results often point to a human-made source near the well.
Does boiling water remove nitrate?
No. MDH warns that boiling makes nitrate more concentrated because water evaporates and the nitrate stays behind. If your well is above 10 mg/L, use bottled water or another safe alternative for drinking and for infant formula, and have a licensed well contractor inspect the well.
How do I get nitrate out of my well water?
MDH recommends first having a licensed well contractor inspect the well and removing nitrate sources on your property. Home treatment can follow. MDH's guidance lists anion exchange, reverse osmosis, and distillation among options, and advises certified units. Babies under six months should still not drink treated water, and retest after treatment.
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