See what your water test results mean
Have a lab report for your tap or well water? Upload it and our team will email you a free, plain-English reading of every result — or type your numbers into the instant reader for an in-browser check against EPA limits. It works for both tap and well.
The instant reader is educational and runs entirely in your browser — nothing you type is uploaded or stored. It compares your own measured numbers to the EPA maximum contaminant level (MCL) or health goal (MCLG).
Confirm any concerning result with a 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 CONCENTRATES nitrate and arsenic, making those results worse.
EPA standards reference
The limits the reader 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 | 10 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) |
| Antimony | 6 µg/L | Primary (health) |
| Cadmium | 5 µg/L | Primary (health) |
| Chromium (total) | 100 µg/L | Primary (health) |
| Mercury | 2 µg/L | Primary (health) |
| Thallium | 2 µg/L | Primary (health) |
| Beryllium | 4 µg/L | Primary (health) |
| Cyanide | 200 µg/L | Primary (health) |
| Atrazine | 3 µg/L | Primary (health) |
| PFOA | 4 ppt | Primary (health) |
| PFOS | 4 ppt | Primary (health) |
| Radium (226+228) | 5 pCi/L | Primary (health) |
| Gross alpha | 15 pCi/L | Primary (health) |
| Total trihalomethanes (TTHMs) | 80 µg/L | Primary (health) |
| Haloacetic acids (HAA5) | 60 µg/L | Primary (health) |
| Chlorine | 4 mg/L | Primary (health) |
| Chloramine | 4 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 |
| Hexavalent chromium (chromium-6) | No single federal limit | Primary (health) |
| Radon | No single federal limit | Primary (health) |
| Total PFAS | No single federal limit | Primary (health) |
| Turbidity | No single federal limit | Primary (health) |
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.
Reading your water test results — FAQ
Do you store or send my results anywhere?
The instant reader runs entirely in your browser — nothing you type is uploaded, saved, or sent to a server. If you upload a report for a full written reading, we store that file privately only to interpret it and reply to you; individual results are never published, only anonymized area-level summaries.
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 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 water 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.
How do I get a full written report?
Upload a photo or PDF of your test and leave your email. Our team reads every report by hand and emails you a full, plain-English interpretation of each result — usually within one business day. It is free and educational, not lab or medical advice.
By TapWaterData Editorial · Standards: U.S. EPA primary and secondary drinking water regulations.
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