"<" is not zero
A result below a reporting limit tells you a range, not an exact amount. A high reporting limit can prevent a useful comparison.
WATER TESTS, WITH CONTEXT
A number is a start.
Not the whole story.
Read your water-test report against WHO references. Understand the units, keep the uncertainty, and leave with better questions for your lab.
Read a testFree. No account. No result uploads.
No overall safety verdict.
A handful of results cannot certify water as safe or drinkable. This is an educational reader, not medical advice or a replacement for a certified lab.
01 / TRANSCRIBE
Bring the report.
Keep its exact meaning.
Enter one sample at a time. Use the lab’s units and "less than" signs. Blank or untested results are never treated as zero. National standards differ from WHO guidance.
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All results in this list must belong to the same water sample. One result per parameter. Start over for a different sample.
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02 / UNDERSTAND THE LIMITS
The signs matter.
Units change the reading
1 mg/L = 1,000 µg/L. Nitrate "as N" differs from nitrate ion. ppm, ppb and conductivity need lab confirmation, not a silent conversion.
Below is not a guarantee
A comparison covers only the value you entered. Sampling, uncertainty, untested hazards, changing conditions and national rules still matter.
03 / THE REFERENCE DESK
Sources beside every reading.
WHO Guidelines for Drinking-water Quality: Fourth edition incorporating first, second and third addenda, 17 June 2026. Reference values are not automatically national legal limits. WHO does not endorse this independent tool. Our explanations and questions are plain-language interpretations, not quotations from WHO.
Offline references are a dated snapshot, not live updates. Official source links need an internet connection. Checking offline availability…
Unit conversions and comparison rules
Micrograms to milligrams: divide by 1,000. WHO’s published factors: 1 mg/L nitrate ion = 0.226 mg/L nitrate-N; 1 mg/L nitrite ion = 0.304 mg/L nitrite-N. Results as N are divided by the relevant factor before comparison. Rounded conversion factors and lab uncertainty can matter near a reference.
Laboratory chemical readings receive comparisons. Screening estimates are not confirmed laboratory exceedances; an estimate suggesting an above-reference value prompts confirmation and professional advice. Less-than results retain their upper bounds; greater-than results retain their lower bounds. The nitrate + nitrite check uses both same-sample results and never fills missing results with zero.
pH, turbidity, TDS, hardness and iron receive no health-based pass/fail. Lead’s provisional value is explicitly not health-based. No green "safe" band or invented "health-significant" tier is used.
04 / YOUR DEVICE, YOUR CHOICE
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This tool offers no treatment dosing, diagnosis or certification. It cannot assess an untested substance or replace local professional advice.