Well Water Test Results Interpreter
Got a lab report back from your private well and not sure what the numbers mean? Enter each result below and this tool compares it to the relevant EPA limit or secondary standard — and tells you what it means and what to do next.
This tool is educational and runs entirely in your browser — nothing you enter is uploaded or stored. It reads your own measured numbers, so the county-level USGS area-estimate disclaimer used elsewhere on this site does not apply here.
Confirm any concerning result with your state-certified lab and retest before choosing a treatment system — lab results vary between samples.
Do not boil water to “fix” nitrate or arsenic. Boiling kills bacteria but it CONCENTRATES nitrate and arsenic, making those results worse, not better.
EPA standards reference
The limits this tool compares your results against. Primary standards are health-based (MCLs and lead/copper action levels); secondary standards are aesthetic; hardness is descriptive only.
| Contaminant | Standard | Type |
|---|---|---|
| Arsenic | 10 µg/L | Primary (health) |
| Nitrate (as N) | 10 mg/L | Primary (health) |
| Nitrite (as N) | 1 mg/L | Primary (health) |
| Lead | 15 µg/L | Primary (health) |
| Copper | 1.3 mg/L | Primary (health) |
| Uranium | 30 µg/L | Primary (health) |
| Fluoride | 4 mg/L | Primary (health) |
| Selenium | 50 µg/L | Primary (health) |
| Barium | 2 mg/L | Primary (health) |
| Total coliform bacteria | Absent (present/absent) | Primary (health) |
| E. coli | Absent (present/absent) | Primary (health) |
| Iron | 0.3 mg/L | Secondary (aesthetic) |
| Manganese | 0.05 mg/L | Secondary (aesthetic) |
| Sulfate | 250 mg/L | Secondary (aesthetic) |
| Chloride | 250 mg/L | Secondary (aesthetic) |
| Total dissolved solids | 500 mg/L | Secondary (aesthetic) |
| Zinc | 5 mg/L | Secondary (aesthetic) |
| pH | 6.5–8.5 | Secondary (aesthetic) |
| Hardness | soft ≤60 · moderately hard ≤120 · hard ≤180 · very hard >180 | Descriptive |
Need to test or retest?
Confirm any result with a lab certified by your state. We list certification programs by state so you can find an accepted laboratory near you.
Interpreting well water results — FAQ
Does this tool store or send my results anywhere?
No. Every value you enter is compared to the standards entirely in your browser. Nothing you type is uploaded, saved, or sent to a server — close the tab and the numbers are gone. The only form on the page that contacts us is the optional email newsletter, which never includes your test values.
What is the difference between a primary and a secondary standard?
A primary standard (MCL or action level) is health-based — exceeding it can affect your health, like arsenic above 10 µg/L or nitrate above 10 mg/L. A secondary standard (SMCL) is aesthetic — it affects taste, smell, color, or staining, like iron above 0.3 mg/L, and is not a health limit on its own.
Can I boil my well water to make a bad result safe?
Only for bacteria, and only as a short-term step. Boiling kills bacteria, but it CONCENTRATES nitrate and arsenic rather than removing them, so boiling makes those results worse, not better. Use an alternate or treated water source for nitrate and arsenic until the well is tested and treated.
My result is right at the limit — is that OK?
A value at or below the EPA limit is reported here as within the standard, but limits are not a guarantee of zero risk, and lab results vary between samples. The honest step for any value near a limit is to retest with a state-certified lab to confirm before deciding whether to treat.
Why doesn't the county area-risk disclaimer apply here?
Elsewhere on this site we publish county-level USGS area estimates, which describe a region and cannot predict a single well. This tool is different: it reads the actual measured numbers from your own well's lab report, so it reflects your specific water — not an area model.
By TapWaterData Editorial · Standards: U.S. EPA primary and secondary drinking water regulations.
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