Calculators / Water and gutters

What do my well water test results mean?

Put in whatever your lab tested. Each result is checked against EPA's health limits and taste and staining guidelines, with what usually treats it.

Updated November 2026 · How we check our numbers

Safe, with taste or staining issues

2 over a guideline

Nothing over a health limit. Iron, pH are past EPA's taste and staining guidelines.

Health limits: OK
Guidelines: 2 over
Results read: 11

Estimate for planning only, not professional advice. Check the manufacturer’s instructions, your local code and a licensed professional before you buy, build or install. Use at your own risk. Terms.

Size a softener12.3 grains per gallon

Your results

EPA limits and guidelines

Total coliformEPA goal: none
Absent
Good. Retest every year.
E. coliEPA goal: none
Absent
Good. Retest every year.
Nitrate (as N)3.2 mg/L; EPA limit 10
OK
Under EPA's number.
Arsenic4 µg/L; EPA limit 10
OK
Under EPA's number.
Lead2 µg/L; EPA action level 15
OK
Under EPA's number.
Copper0.2 mg/L; EPA action level 1.3
OK
Under EPA's number.
Iron0.6 mg/L; EPA guideline 0.3
Over guideline
Rust stains and metallic taste. An oxidizing filter, or a softener for small amounts.
Manganese0.02 mg/L; EPA guideline 0.05
OK
Under EPA's number.
Total dissolved solids280 mg/L; EPA guideline 500
OK
Under EPA's number.
pH6.3; EPA guideline 6.5 to 8.5
Corrosive
Acidic water corrodes pipes and can pick up lead and copper. An acid neutralizing filter raises it (it can add hardness).
Hardness210 mg/L, 12.3 grains per gallon
Very hard
Not a health issue (EPA sets no standard), but it scales fixtures and water heaters. A softener fixes it.

Test every year

EPA and CDC say to test a private well every year for total coliform bacteria, nitrates, total dissolved solids and pH.

Private wells

EPA doesn't regulate private wells, so these are the public water limits used as a yardstick. Your state or county health department can help read a report.

Lead is dropping to 10

EPA's lead action level for public water drops from 15 to 10 µg/L on November 1, 2027. The goal for lead is zero.

How we work it out

EPA doesn't regulate private wells, so we compare your results with the limits it sets for public water. Health limits (MCLs and action levels): nitrate 10 mg/L as N, nitrite 1, arsenic 10 µg/L, lead 15 µg/L (10 from November 1, 2027), copper 1.3 mg/L, fluoride 4, uranium 30 µg/L, and no coliform bacteria.

Taste and staining guidelines (secondary standards, not enforced): iron 0.3 mg/L, manganese 0.05, sulfate 250, chloride 250, total dissolved solids 500, pH 6.5 to 8.5. Hardness has no standard; we give USGS's classes: soft up to 60 mg/L, moderately hard to 120, hard to 180, very hard above.

Treatments are from Virginia Cooperative Extension's guide: reverse osmosis for most dissolved inorganic contaminants like nitrate and arsenic (not bacteria), oxidizing filters for iron and manganese, acid neutralizers for low pH, softeners for hardness, and chlorination or UV for bacteria.

Where the numbers come from

Water at home

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