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.
Start with the name on your water bill
In the Inland Empire, a mailing address does not settle which agency supplies you. Parts of Riverside are served by Western Municipal Water District, and parts of San Bernardino near Highland by East Valley Water District, each with its own report. The figures above run from 7.3 gpg in Rancho Cucamonga to 14.2 in San Bernardino, so the county name tells you little. Check your bill, open your city's page, then book a free in-home water analysis with the form below. We read your tap and compare it with the agency that serves your address.
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.
Who is the best water filtration company in the Inland Empire?
Compare companies on six things you can check, not on who says they are best. (1) A free analysis of your own water before any quote. (2) Independent certifications: ask for the certificate and look it up with the certifier. (3) What the tanks, valves and media are made of, with flow ratings in writing. (4) A written warranty with a term for each part, because these systems are not cheap. (5) How long the company has been around: a warranty is only as good as the company behind it, and a warranty from a company that is gone is a worthless piece of paper and a big tank in your garage with nobody to call. (6) Reviews you can read. Nuvia Water offers a free in-home water analysis in the Inland Empire, was founded in 2012, holds California license 969902 (C-55 Water Conditioning), is BBB Accredited with an A rating, has a 4.6 Google rating from more than 1,600 reviews, and backs its Nuvia Pro dual-tank system with a 15-year media warranty and a 10-year control valve warranty. Nuvia's materials carry marks from IAPMO R&T, NSF, cUL us, UPC and ISO 9001 and 14001. Ask any company, including us, for the same papers.
Book your free water analysis today.
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