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Contaminants

Well water contaminants and what the numbers mean

A lab report is a column of figures with no interpretation attached. Each page here covers one of them: what level matters, which standard applies and whether it is about health or about stains.

Staining, taste and equipment

These make water unpleasant and wreck plumbing. They are not health hazards at typical well levels.

  • Hard water from a well

    No federal standard

    Dissolved calcium and magnesium. It scales water heaters, coats fixtures, stops soap working, and shortens the life of every appliance that heats water.

  • Hydrogen sulfide in well water

    No federal standard

    The rotten egg smell, and the one water problem people notice instantly. Your nose finds it at concentrations a lab would call trace, and the treatment depends entirely on how much there is.

  • Iron in well water

    0.3 mg/L

    The most common well water complaint in the country. Above 0.3 ppm it stains everything water touches, and the form it arrives in decides whether a filter or a softener is the right answer.

  • Manganese in well water

    0.05 mg/L

    Iron's quieter companion. It stains black or grey rather than orange, shows up at a twentieth of iron's concentration, and needs a distinctly higher pH to remove.

  • Low pH (acidic) well water

    6.5 to 8.5

    The measurement that quietly decides more than any other number on the report. Low pH dissolves plumbing, and it slows the oxidation that every iron filter depends on.

Health contaminants

These route to a certified lab and your health department. No page here ends in a product recommendation for them.

  • Coliform and E. coli in well water

    Zero total coliform

    The one result that is about the well's physical condition rather than the water's chemistry. Bacteria in a well mean something is getting in, and disinfection treats the consequence rather than the cause.

  • Nitrate in well water

    10 mg/L as nitrogen

    A genuine health standard rather than a staining threshold, and the population at risk is infants under six months. It is also a signal about the well itself, because nitrate is not naturally abundant in deep groundwater.