Match the city to its public water system
Every record begins with a city, utility or named service area. TapSure checks who supplies the destination and whether the evidence represents treated water in the distribution system, a customer tap, a treatment plant, raw water, a private well or a single building. Evidence is not expanded beyond its demonstrated coverage. A plant result, isolated property or national statistic cannot by itself prove every faucet in a city.
Use a documented source hierarchy
Priority goes to water utilities, drinking-water regulators, public health authorities, government laboratories and current compliance reports. Government travel-health guidance establishes a conservative traveler baseline. Peer-reviewed research and qualified laboratories may provide limited historical or directional context when their sampling, units and public-supply connection can be reproduced. Commercial pages are not treated as verified local measurements without traceable primary evidence. National and international estimates remain fallback context.
Reopen and reproduce the evidence
Researchers record the publisher, direct HTTPS source, reporting period, publication date, sample stage, service coverage, statistic and material limitations. Values are checked against the original table or result whenever possible. Important, disputed or ambiguous conclusions receive an independent recheck. Conflicting evidence is retained in the audit and resolved conservatively rather than averaged away.
Classify the drinking-water guidance
The four results describe what the evidence supports for a traveler. They are not a simple laboratory grade and do not guarantee an individual building or faucet.
Normally drinkable public supply
Current city or utility-service-area evidence supports normally drinking the treated public supply, and no applicable official traveler source tells visitors to avoid it. An explicit government traveler statement that tap water is safe may be used only as a country-scoped, limited-confidence fallback; silence is never proof. Private wells, rooftop tanks, internal plumbing and temporary incidents remain outside this conclusion.
An important uncertainty remains
This does not automatically mean the public network is unsafe. It is used when building pipes or tanks, multiple service areas, intermittent supply, older evidence, incomplete customer-tap coverage, a minor unresolved compliance issue or conflict between local utility evidence and broader traveler advice prevents a simple city-wide conclusion. Confirm the exact property supply or use appropriate treatment.
The conservative traveler baseline
An official government health or traveler source recommends sealed bottled, boiled or properly treated water, and equally current local evidence does not establish direct-drinking suitability through the distribution network or monitored customer taps. This is a monthly baseline, not a live emergency alert, and does not mean every public sample failed. Treatment should match the actual risk.
No dependable direction can be supported
The search found neither current city-level compliance evidence nor an explicit traveler recommendation strong enough for another result. Missing evidence is not proof that the water is safe or unsafe. TapSure recommends a conservative alternative until the exact supply can be confirmed.
Explain evidence scope and confidence
- City guidance: the evidence explicitly addresses the named city.
- Utility service area: the evidence covers a named network that may not include every city address.
- Country guidance: an official traveler-health fallback, never proof for a hotel, building or faucet.
- High confidence: current direct local evidence with a clear conclusion and identifiable boundary.
- Medium confidence: official evidence with material last-mile, age or source-conflict limits.
- Limited confidence: country fallback, inaccessible city detail or incomplete local evidence.
Approve a hardness number only when every gate passes
A value does not become a TapSure measurement simply because a page calls the water hard. To show a verified number, TapSure must reproduce the correct parameter, water stage, unit, statistic, geography, period and source. Two independent evidence reviews must reach the same conclusion.
Total hardness
The source must explicitly report total hardness or an equivalent total-hardness measurement—not calcium alone, calcium hardness, alkalinity, TDS or conductivity.
Public supplied water
The evidence must represent treated supply, distribution water or monitored customer taps. Raw water, rivers, wastewater, bottled water and unrelated private wells are excluded.
Known unit basis
The value must be expressed as calcium carbonate or have a separately cited authoritative basis. An unresolved unit does not get converted.
Matched service area
The utility, zone, plant or sample must be demonstrably linked to the displayed city. A nearby city or regional geology map is not enough.
Preserved statistic
An exact value, mean, median, range or named-zone result remains the statistic the publisher reported. TapSure does not silently turn one type into another.
Traceable and reviewed
The original value, unit, reporting period, source locator and limitations are retained, and different reviewers independently reproduce the evidence.
Normalize units without guessing
Accepted results are normalized to mg/L as CaCO₃ so that different publishers can be compared on one scale. A conversion is used only when the source explicitly measures total hardness and its unit basis is documented. The original value and unit remain visible in the source area.
| Published unit | Release normalization | Required condition |
|---|---|---|
| mg/L as CaCO₃ | Keep the value | The parameter is explicit total hardness. |
| ppm as CaCO₃ | 1:1 | The CaCO₃ basis is explicit or independently documented. |
| US grains per gallon | × 17.1 | The paired unit and CaCO₃ convention are reproducible. |
| French degrees (°fH) | × 10 | An authoritative source defines the unit basis. |
| Reviewed German degrees (°dH) | × 17.8 | Only an approved conversion route with cited basis is used. |
| mg/L as CaO | × 1.785 | The source explicitly reports hardness as CaO. |
| mmol/L | × 100.09 | The source explicitly reports total hardness. |
| Water ppb | ÷ 1,000 | Total hardness and its CaCO₃ convention are established. |
Each conversion is retained in the audit and checked independently. The App may also divide the approved canonical value by 17.1 to show grains per gallon for convenience. That display conversion is not new source evidence. If the parameter or basis is unclear, the number is not promoted to a verified profile.
Keep averages, ranges and supply zones honest
- Published value: one applicable system value or observation remains a value.
- Published average: a mean may orient the main gauge only when the publisher calls it a mean or average.
- Published median: a median remains a median and is not relabelled as an average.
- Published range: both endpoints and every band crossed remain visible.
- Named supplies or zones: materially different systems remain separate unless the publisher supplies a valid city summary.
TapSure never calculates an average from only the minimum and maximum. If a publisher gives a mean of 105 mg/L and a range of 80–140 mg/L, the App may say Moderately hard on average while still showing the complete moderately-hard-to-hard range. If two unmapped supplies publish 50 and 210 mg/L, the result is Variable by supply area, not an invented 130 mg/L city average.
Open evidence stays open: <5 does not become zero or five,
and 30+ does not receive an invented maximum. The qualifier
remains visible.
Why some results say “Likely”
Likely is a precision label. It means qualified evidence supports a broad hardness direction, but not a defensible current number for the whole city or the traveler’s exact address. It is used when one or more exact-value gates fail without destroying the overall direction.
For a Likely result, the supporting numeric work remains in the research audit. The public App stores only the band, evidence basis, confidence, service area, source and limitations. It removes the number and gauge so the interface does not imply false precision.
Show the highest evidence layer the source can support
Verified measurement
The parameter, unit, public-supply relationship, statistic, service boundary and source are reproducible. An exact value, publisher average, range or named zones and a gauge may be shown.
Official category only
A current utility or regulator explicitly publishes a total-hardness category for the applicable supply but no defensible number. No endpoint or gauge is invented.
Research or historical reference
A published public-supply number is reproducible, but age, limited coverage or incomplete metadata prevents a verified badge. Its year and limits stay visible.
Indicative hardness
Qualified evidence supports a broad direction but not an exact current local value. The App shows Likely or Variable with medium or limited confidence and no number.
Estimated hardness
A controlled historical study, specification, source-linked proxy or mixed-supply record supports direction only. It is low confidence, clearly labelled and has no number or gauge.
Measurement unavailable
No reliable local value or defensible direction survived review. TapSure explains what was missing instead of forcing a soft or hard label.
Apply one general hardness scale
TapSure applies the USGS general classification to normalized total hardness. Publisher terminology is retained separately when a utility or regulator uses different thresholds.
- Soft: 0–60 mg/L as CaCO₃
- Moderately hard: above 60–120 mg/L as CaCO₃
- Hard: above 120–180 mg/L as CaCO₃
- Very hard: above 180 mg/L as CaCO₃
- Variable: qualified values cross bands or named supplies differ materially
Validate, review and disclose limits
Release checks verify the data schema, unique IDs, dates, HTTPS sources, evidence fields and status rules. The guide follows a monthly review schedule. Temporary boil-water or do-not-drink notices can arise after a record is reviewed, and conditions inside a building may differ from the public network. Travelers should check the local utility or health authority when conditions change. TapSure is travel guidance, not medical advice or a guarantee for an individual tap.