Hardness by city in the Inland Empire
The Inland Empire here means Riverside and San Bernardino counties. Hardness is measured in grains per gallon (gpg). The U.S. Geological Survey calls water hard from 7.1 to 10.5 and very hard above 10.5. Each row is the figure the water agency published for its own customers, with a link to its report. A single number is the agency's average. A range means the agency blends sources that differ or reports them separately, so the table shows the lowest and highest source average instead of one number.
Riverside County
| City | Water agency | Hardness | Basis | Report |
|---|---|---|---|---|
| Corona | City of Corona | 8.5 gpg | printed | City of Corona Consumer Confidence Report (2025) |
| Riverside | Riverside Public Utilities | 12 gpg | printed | Riverside Public Utilities Water Quality Report (2025) |
| Eastvale | Jurupa Community Services District | 9.5 gpg | calculated from mg/L | Jurupa Community Services District Water Quality Report (2025) |
| Temecula | Rancho California Water District | 8.8 to 13.5 gpg | calculated from mg/L | Rancho California Water District Consumer Confidence Report (2025) |
San Bernardino County
| City | Water agency | Hardness | Basis | Report |
|---|---|---|---|---|
| San Bernardino | San Bernardino Municipal Water Department | 14.2 gpg | calculated from mg/L | San Bernardino Municipal Water Department Consumer Confidence Report (2025) |
| Rancho Cucamonga | Cucamonga Valley Water District | 7.3 gpg | calculated from mg/L | Cucamonga Valley Water District Water Quality Report (2025) |
City pages
- Corona: City of Corona, 8.5 gpg, hard.
- Eastvale: Jurupa Community Services District, 9.5 gpg, hard.
- Rancho Cucamonga: Cucamonga Valley Water District, 7.3 gpg, hard.
- Riverside: Riverside Public Utilities, 12 gpg, very hard.
- San Bernardino: San Bernardino Municipal Water Department, 14.2 gpg, very hard.
- Temecula: Rancho California Water District, 8.8 to 13.5 gpg, hard to very hard.
Why the Inland Empire has no single number
The agencies here do not share a supply. Corona's report lists three sources that range from moderately hard to very hard, and the system average sits between them. Riverside's utility blends its groundwater at one central location, which keeps its range narrow. San Bernardino's department reports groundwater only. Some addresses are served by a different agency than the city on the mailing address, so your water bill is the first thing to check.
Local rules on water-conditioning equipment also differ by city and by sewer agency. Corona has its own city code on residential water-conditioning equipment, and each city page here says what we found for that city.
What Nuvia does in the Inland Empire
Nuvia Water offers a free in-home water analysis, so you can see your own tap's numbers next to your agency's average. Book it with the form below.
Sources
Questions people ask
How hard is the water in the Inland Empire?
It depends on the city and the agency. The City of Corona reports 8.5 gpg, which it classifies as hard. Riverside Public Utilities prints 12 gpg and the San Bernardino Municipal Water Department reports 14.2 gpg, and both are very hard on the USGS scale.
Why do neighboring cities have different numbers?
Each city is supplied by its own agency, and the agencies draw on different sources. Corona blends State Water Project water, Colorado River water and local groundwater. Riverside blends groundwater from two basins. San Bernardino reports that all of its supply is groundwater from the Bunker Hill Basin.
Which Inland Empire cities does Nuvia have pages for?
Corona, Eastvale, Rancho Cucamonga, Riverside, San Bernardino and Temecula. We add a city when we have read its agency's own report.
How do I find my water agency?
Your water bill names it. The agency is not always the city on your mailing address, so check the bill before you rely on a city's number.
Does the in-home water analysis cost anything?
No. Nuvia Water offers it free. Book it with the form on this page or with the Book button.
Book your free water analysis today.
A Nuvia specialist tests your water at your tap and shows you the numbers.