The table
The year in brackets is the year the water was sampled. The basis column says whether the agency printed the grains-per-gallon figure or whether we converted its printed mg/L figure at 17.1 mg/L per grain.
How to read it
Hardness is calcium and magnesium dissolved in water. It shows up as scale on fixtures, spots on glass and buildup inside water heaters. The U.S. Geological Survey sorts it into four bands.
| Band | Grains per gallon | mg/L |
|---|---|---|
| Soft | 0 to 3.5 | 0 to 60 |
| Moderately hard | 3.6 to 7.0 | 61 to 120 |
| Hard | 7.1 to 10.5 | 121 to 180 |
| Very hard | Above 10.5 | Above 180 |
- One number is the agency's average for its customers.
- A range means the agency reports its sources separately or blends sources that differ. The table shows the lowest and highest source average.
- An average is not your tap. It is the system or source average over the sampling year, so a reading at one home on one day can differ.
- Your supplier is not always your city. The agency on your water bill is the one that counts, and the table names the agency behind each row.
What this table leaves out
A city is not in the table until we have read its agency's own report. Cities served by several agencies, with no single report that covers them, are left out rather than guessed. Third-party websites and answer tools sometimes publish a different number for the same city. This table uses only the agency's report, and each row links to it.
Cities with a Nuvia page
The county pages are Orange County and the Inland Empire.
See your own number
Nuvia Water offers a free in-home water analysis, so you can see your own tap's numbers next to your agency's average.
Questions people ask
What does gpg mean?
Grains per gallon, the unit water agencies use for hardness. One grain per gallon is 17.1 mg/L of hardness, the factor the agencies themselves use to convert between the two.
Why do some rows show a range?
A range means the agency reports its sources separately or blends sources that differ. We show the lowest and highest source average rather than one number that would hide the spread.
What does the year in brackets mean?
It is the year the water was sampled. Some agencies had not posted a newer report when we read theirs, so a few rows are a year behind the others.
Why does this table differ from other websites?
Websites and answer tools sometimes show a different number for the same city. This table uses only the agency's own report, and every row links to it so you can check it.
Is this the hardness of my own tap?
No. An agency figure is an average for its system or its sources over the sampling year. A reading at one home on one day can be higher or lower.
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