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Well Water Testing · Stockton, MN

Water testing in Stockton

Water testing for Minnesota homes, above all those on a private well. An accredited laboratory tests the water for coliform bacteria and E. coli…

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Stockton · Winona County

Well Water Testing in Stockton

Water testing for Minnesota homes, above all those on a private well. An accredited laboratory tests the water for coliform bacteria and E. coli, nitrate, arsenic, lead, manganese, VOCs (volatile organic compounds), DRO (diesel range organics), iron, hardness, pH, fluoride, sulfate and uranium. The Minnesota Department of Health recommends testing a private well for coliform bacteria every year, nitrate every other year, and arsenic and lead at least once.

Stockton is a small valley town on Garvin Brook with a real flash-flood history. Housing here runs to small valley-town homes with a flash-flood history, across the Garvin Brook valley core.

Questions about a Stockton home?  ·  Call or text (612) 457-1634

Well water in Winona County

MDA tested 13 Winona County townships in 2016-2017. The initial dataset of 940 wells had 19.1% at or above 10 mg/L nitrate-nitrogen. After removing 209 wells with other likely nitrate sources or well problems, the final dataset of 731 wells was 7.1%, and four townships were over 10%. Fremont was highest at 42.9%, followed by Utica at 19.6%. MDH describes karst as the most common geology in southeast Minnesota, where surface water can reach groundwater in hours or days.

County facts checked October 2026 against: mda.state.mn.us, mda.state.mn.us, Minnesota Department of Health.

Well water around Stockton, Winona County

Stockton, MN water testing: well cap in the foreground, ranch home on acreage behind it in the Minnesota River valley in summer
Nitrate: EPA limit 10 mg/L, highest risk to infants →
Well cap in the foreground, split-level home on a wooded lot behind it in the Minnesota River valley in winter snow (Winona County, Minnesota)
Coliform bacteria: MDH recommends testing every year →

See all Stockton inspections →  ·  More about well water testing →  ·  Every water test, explained →

Water tests available in Stockton

Bacteria

Shows whether surface water or waste is reaching the well.

  • Total coliform bacteria
    Surface contamination reaching the well
    None should be present (MDH)
  • E. coli
    Fecal contamination from septic, manure or wildlife
    None should be present (MDH)

Health chemicals

No taste, color or smell. These are the long-term health checks.

  • Nitrate
    Fertilizer, septic and manure; highest risk to infants
    10 mg/L (EPA)
  • Arsenic
    Natural arsenic from Minnesota rock and soil
    10 µg/L (EPA)
  • Lead
    Lead service lines, solder and brass fixtures
    No safe level (MDH)
  • Manganese
    Natural manganese; a concern for infants
    100 µg/L for infants (MDH guidance)
  • Fluoride
    Natural fluoride; dental health
    4.0 mg/L (EPA)
  • Uranium
    Natural radionuclide in groundwater
    30 µg/L (EPA)

Petroleum & solvents

Fuel and chemical spills from old tanks or nearby sites.

  • VOCs (volatile organic compounds)
    Fuels, solvents, degreasers and paints
    Varies by compound (EPA)
  • DRO (diesel range organics)
    Diesel and heating-oil petroleum
    No limit of its own; a petroleum screen (MPCA)

Household quality

Staining, scale and taste, and choosing the right treatment.

  • Iron
    Rusty staining and metallic taste
    0.3 mg/L, aesthetic (MDH)
  • Hardness
    Scale buildup; sizing a water softener
    No health standard
  • pH
    Corrosive or scaling water
    6.5 to 8.5, aesthetic (EPA)
  • Sulfate
    Taste and odor; diarrhea risk for infants
    250 mg/L, aesthetic (EPA)

Limits from MDH, EPA and MPCA. Your lab report compares each result to these values.

Stockton private well testing timeline

Minnesota Department of Health schedule: coliform bacteria every year, nitrate every other year, arsenic and lead at least once. Source: MDH
TestYear 1Year 2Year 3Year 4Year 5Year 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.

Nitrate in Winona County wells

7.1%

7.1% of 731 wells tested in 13 townships (final dataset) were at or over the 10 mg/L nitrate standard (MDA township testing, 2016-2017).

Source: Minnesota Department of Agriculture township testing

Township numbers are averages. Only a test of your own well tells you its nitrate level. Get a free instant quote

Buying a home with a well in Stockton: the disclosure rules

  1. Before the purchase agreementThe seller discloses in writing every known well and whether it is in use, not in use or sealed.
  2. At closingA well disclosure certificate is signed, unless the deed says the seller knows of no wells.
  3. If a well was hiddenA seller who knew of an undisclosed well can owe the sealing cost and attorney fees if the buyer sues within six years.
Source: Minnesota Statutes 103I.235

The disclosure tells you a well exists, not what is in it. Add water testing to your inspection. Get a free instant quote

How far a well must be from common hazards in Stockton

  • 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
Source: Minnesota Rules 4725.4450 and 4725.4350

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

Questions

Common questions.

Who needs well water testing?
Any home on a private well, and above all when you are buying one. A private well is not regulated like a city water system, so the owner is responsible for knowing what is in the water. Testing before closing tells you whether the water needs treatment while you can still ask questions or negotiate.
What does the water panel cover?
The panel covers coliform bacteria and E. coli, nitrate, arsenic, lead, manganese, VOCs (volatile organic compounds), DRO (diesel range organics), iron, hardness, pH, fluoride, sulfate and uranium. Bacteria and nitrate are the short-term health checks. Arsenic, lead, manganese and uranium are the ones you cannot see or taste. VOCs and DRO screen for solvents and petroleum, such as fuel from an old oil tank or a nearby leak site. Iron, hardness, pH and sulfate explain staining, scale, odor and wear on plumbing and appliances.
How often should a well be tested?
The Minnesota Department of Health recommends coliform bacteria every year, nitrate every other year, and arsenic and lead at least once. Test again after flooding, after any work on the well, or if the taste, color or smell of the water changes.
Is well water testing part of the home inspection?
It is an add-on. Add it to your home inspection quote. Testing early in your inspection window leaves time to act on the results.
Which Winona County townships had the highest well nitrate?
In MDA's 2016-2017 final dataset of 731 wells, Fremont Township had 42.9% of wells at or above 10 mg/L, then Utica at 19.6% and St. Charles at 14.5%. The county total was 7.1%. Those are township samples, not a prediction for your property.
My home is on city water. Is water testing still worth it?
Often yes. Community water systems follow EPA testing rules and report results in an annual Consumer Confidence Report, but that report does not measure your own plumbing. MDH and EPA say lead enters mainly from service lines and plumbing materials, and the only way to know is a tap test. MDH recommends an accredited lab, and your utility can say whether your home has a lead service line.
When should a home be tested for DRO or VOCs?
MDH suggests considering a VOC test when a well is near fuel tanks or a commercial or industrial area. MPCA reports petroleum has leaked at about 22,000 Minnesota sites, including home heating-oil tanks, and releases can threaten drinking water and send vapors into buildings. Reasons to test include a nearby leak site, a former or buried fuel tank, or a fuel odor or sheen. MPCA's leaking-tank-site database shows reported releases.
Does Stockton's flood history matter?
Very much — the 2007 flood hit this valley hard, so flood evidence, elevation of mechanicals and drainage improvements are things we specifically look for.
How do you get rid of VOCs in well water?
MDH advises first removing the source of contamination or using a safer water supply. If that is not possible, home treatment may be appropriate, and some technologies can reduce VOCs depending on the filter media. Choose a certified unit, use a licensed plumber or water conditioning contractor, and retest after installation.
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.
Who regulates private wells in Minnesota, and who is responsible for the water?
The Department of Health licenses the contractors who construct, repair, and seal regulated wells, and administers the Well Code, Minnesota Rules chapter 4725. For an existing private well, the Department of Health says the owner is responsible for regularly testing the water and keeping it safe. Licensed contractors must file well records, and since 1974 the Department of Health has required submittal of well construction records. Water testing arranged by the owner fills that gap.
How can I tell if there is a forgotten well on my property?
The Department of Health suggests looking for a pipe 1 to 8 inches wide at, above, or below the surface, a low spot or sunken area, a metal, wood, or concrete cover, a windmill or old well house, and a concrete patch or glass block in a basement step or floor. Well pits and basement offsets are other common signs. Visible signs like these are worth raising with your agent and a licensed well contractor.
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