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Well Water Testing · Oakdale, MN

Water testing in Oakdale

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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Oakdale · Washington County

Well Water Testing in Oakdale

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.

Oakdale is an east-metro suburb of 1970s-90s subdivisions. Housing here runs to 1970s-90s subdivisions, across the east-metro subdivisions.

Oakdale is served by our Saint Paul team →  ·  (612) 457-1634

Well water in Washington County

MDA's 2014-2015 township testing in Washington County covered Cottage Grove and Denmark. The final dataset held 441 wells with 15.0% at or over the 10 mg/L nitrate-nitrogen health risk limit. Cottage Grove (city) was 20.2% and Denmark 8.3%. MDA said Cottage Grove had more than 10% of wells over the limit. MDH lists coliform yearly, nitrate every other year, and arsenic and lead at least once.

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

Private wells and water systems around Oakdale

Oakdale, MN water testing: well cap in the foreground, cabin with a stone chimney behind it on a Minnesota lake in winter snow
Coliform bacteria: MDH recommends testing every year →
Well cap in the foreground, lake home with a sloping lawn behind it on a Minnesota lake in autumn color (Washington County, Minnesota)
Nitrate: EPA limit 10 mg/L, highest risk to infants →
Oakdale, MN water testing: well cap in the foreground, log cabin behind it on a Minnesota lake in summer
Arsenic: about 10% of Minnesota wells exceed the standard →

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

Water tests available in Oakdale

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.

Oakdale 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 Washington County wells

15%

15% of 441 wells tested in Cottage Grove and Denmark were at or over the 10 mg/L nitrate standard (MDA township testing, 2014-2015).

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

How long a private well lasts in Oakdale

0255075100+ years
25 to 50 years is common
100+ possible

Wells built before 1974, when Minnesota's well code began, are listed by MDH as higher risk for bacteria, along with leaking dug wells, wells in old frost pits and wells with corroded casings.

Source: Minnesota Department of Health

Wells built before 1974 often have no record on file. Test the water before you close. Get a free instant quote

Buying a home with a well in Oakdale: 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

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.
Is nitrate high in Washington County wells?
In MDA's 2014-2015 testing, 15.0% of 441 wells were at or over 10 mg/L. Cottage Grove was 20.2% and Denmark 8.3%, so it depends on location.Coliform bacteria and E. coli are the pass-fail items lenders and buyers ask about first.
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.
What should Oakdale buyers expect?
Systems from the 70s-90s at or near end of life, and enough original roofing left in the neighborhood that hail history is worth checking.
Is E. coli in well water dangerous?
It can be. CDC says most E. coli is harmless but some types cause serious illness, and a standard lab test does not identify the dangerous types. Because a positive result points to fecal contamination, treat the water as unsafe to drink until the well is disinfected and retested negative.
What are VOCs in well water?
VOCs, or volatile organic compounds, are a group of organic chemicals found in products such as paints, solvents, pesticides, and petroleum products. EPA notes they can reach private wells through waste disposal, spills, and runoff. A laboratory test is the only way to find out whether any are in your well.
How far must a well be from a septic tank or drainfield?
Under Minnesota Rules 4725.4450, a water-supply well must be at least 50 feet from a septic tank and 50 feet from the absorption area of a typical soil dispersal system or a privy. Sensitive wells need more: 100 feet from the absorption area or privy. Distances are measured from the top of the well casing. A coliform and nitrate test shows whether nearby septic components are reaching the water.
How common is arsenic in Minnesota well water?
The Department of Health says about 40 percent of Minnesota wells have arsenic in the water. It occurs naturally in rocks and soil, levels can differ between wells even within a small area, and you cannot taste, see, or smell it. The EPA limit for community water systems is 10 micrograms per liter. Only a lab test shows the arsenic level in a specific well.
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