About this site and our method
HardnessReport answers one question per city: how hard is the tap water, according to the utility that supplies it?
Rules we follow
- Primary sources only. Each number comes from the utility's own report or data page. We open the document itself. We do not copy from other lookup sites or search snippets.
- Stated as published. We give the average and range the utility gives, in its units, with the report year. If the utility gives no average, range or year, we say so.
- Our math is labeled. Where we convert units, we show the arithmetic: mg/L ÷ 17.1 = gpg.
- Dated. Every page shows a “last checked” date. Utilities publish new reports each year, usually by July 1. We re-check after that.
- Utility, not ZIP code. A ZIP code can be split between water systems. We publish by utility and name the system.
- Hardness only. We do not make health claims. For anything beyond hardness, read the utility's full report.
- Disagreements are noted. If other sites show a different number, we say so and explain likely reasons, without guessing at motives.
The scale we use
| Class (USGS) | mg/L (ppm) as CaCO3 | Grains per gallon (÷ 17.1) |
|---|---|---|
| Soft | 0–60 | 0–3.5 |
| Moderately hard | 61–120 | 3.6–7.0 |
| Hard | 121–180 | 7.1–10.5 |
| Very hard | more than 180 | more than 10.5 |
Limits
A system-wide average is not a reading at your tap. Hardness changes with season, source and plant. Buildings with their own softeners will differ. For your own number, use a home test kit or ask your utility.
Corrections
When a utility publishes a new figure, we update the page and show the new year.