Independent guides for homes on a private well and septic system. We don't sell treatment systems or pumping services.

Well water result checker

Type in the numbers from your lab report and see which ones are over a limit, and what to read next.

Interactive tool

Well water result checker

Fill in only the rows that are on your lab report. Leave the rest empty.

E. coli
Total coliform bacteria

The two ways of reporting have different limits. Check the wording on your report.

Your results against federal benchmarks

Enter a result

Type in any number from your lab report. You do not need to fill in every row.

    • This tool only knows the numbers you typed. It can't tell you the water is safe: a well can have a problem that wasn't on the test.
    • It uses US federal numbers. Your state may set its own, and your lab or health department can explain a result that is close to a limit.

    How this checker works

    A private well isn't covered by federal drinking water rules, so nobody compares your results with a limit for you. Labs usually print the federal numbers for public water systems next to each result, and this tool does the same comparison:

    • Health limits come from EPA's primary drinking water regulations: a goal of zero for total coliform bacteria, 10 mg/L for nitrate measured as nitrogen, 0.010 mg/L for arsenic and an action level of 0.015 mg/L for lead1.
    • Guidelines for iron, manganese, total dissolved solids and pH come from EPA's secondary standards, which are about taste, staining, scale and corrosion and not about health2.
    • Nitrate reported as nitrate is compared with 45 mg/L, the same limit expressed the other way3.
    • Hardness has no federal number. The tool shows where it falls on Penn State Extension's scale8.

    What “worth attention” means

    A result can be under the legal number and still deserve a second look. The tool flags these cases:

    • Nitrate above 3 mg/L as nitrogen. Minnesota's health department says natural processes usually produce less than that4.
    • Arsenic from 5 to 10 µg/L. EPA's health goal is zero1, and Oregon State University Extension advises against using water at 5 µg/L or more for infant formula6.
    • Any lead at all. EPA's goal is zero and it says there is no safe level7.
    • Manganese above 0.1 mg/L. That is the level Minnesota's health department advises for babies under one, below EPA's general advisory of 0.3 mg/L5.
    • Anything over an EPA guideline, such as iron above 0.3 mg/L or a pH outside 6.5 to 8.52.

    Its limits

    • It can't say your water is safe. It only checks what you type in, and a routine test covers a handful of the things that can be in groundwater.
    • It uses US federal numbers. Some states set stricter ones, and Canada's guidelines differ. See well water testing in Canada.
    • Units matter. A result of 0.012 mg/L of arsenic is 12 µg/L. If your report's units aren't in the menus, ask the lab before relying on the comparison.
    • One sample is one day. Results near a limit are worth retesting, and your lab or health department can help interpret them.
    Full guide Well water testing: what to test for, how often, and what it costs

    Sources

    We opened every source below and checked that it says what we cite it for. Numbers in the text, like 1, point to this list.

    1. 1
      National Primary Drinking Water Regulations

      US Environmental Protection Agency (EPA) · Updated Aug 31, 2026 · checked Oct 9, 2026

    2. 2
      Secondary Drinking Water Standards: Guidance for Nuisance Chemicals

      US Environmental Protection Agency (EPA) · Updated May 26, 2026 · checked Oct 9, 2026

    3. 3
      Nitrates in Drinking Water

      Penn State Extension · Updated May 29, 2025 · checked Oct 9, 2026

    4. 4
      Nitrate in Drinking Water

      Minnesota Department of Health · Updated Jun 5, 2026 · checked Oct 9, 2026

    5. 5
      Manganese in Drinking Water

      Minnesota Department of Health · Updated Nov 17, 2025 · checked Oct 9, 2026

    6. 6
      Be Well Project: Arsenic in Your Drinking Water (EM 9401)

      Oregon State University Extension Service · Jun 2023 · checked Oct 9, 2026

    7. 7
      Basic Information about Lead in Drinking Water

      US Environmental Protection Agency (EPA) · Updated Jun 18, 2026 · checked Oct 8, 2026

    8. 8
      Water Softening

      Penn State Extension · Updated Sep 8, 2025 · checked Oct 9, 2026