Preferred source order
- Official utility water quality report or water quality summary.
- Official utility fact sheet or treatment/source-water page.
- State or EPA public water system data.
- Credible secondary source clearly citing an official report.
Secondary values are allowed only as temporary temporary source notes and must be labeled as such.
Units and conversion
Hardness may appear as mg/L as calcium carbonate, ppm as calcium carbonate, or grains per gallon. MyWaterFacts stores the original unit and may also show converted values when the source is clear.
Confidence labels
| Label | Meaning |
|---|---|
| High | Direct official value and unit found. |
| Medium | Official category or secondary value with clear source trail. |
| Low | Hardness not directly reported or provider matching is unresolved. |
Provider-specific hardness
Some cities should not have one citywide hardness number. Houston and Orlando are examples where utility/provider matching matters before showing a hardness value.