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Backflow Testing Services in Ontario, California

Finding a reliable backflow testing professional in Ontario, California is essential for maintaining a safe water supply and staying in compliance with local regulations. Our directory lists 21 backflow testing companies serving Ontario and surrounding communities including Upland, Montclair, Chino.

Whether you need annual backflow testing, RPZ (Reduced Pressure Zone) valve inspection, or cross-connection control services, the providers listed below offer professional testing services for both residential and commercial properties throughout the Ontario area.

Most water authorities in California require annual testing and reporting for all backflow prevention assemblies. A certified backflow tester will inspect your devices, perform the required differential pressure tests, and file compliance reports with your local water authority.

Browse the listings below to compare ratings, read customer reviews, and contact backflow testing professionals near Ontario directly. Use the filters above to narrow results by rating, review count, or specific services like RPZ testing and preventer installation.

Data source: Google Maps. Always verify licensing with your local water authority.

21 listed providers

Services:
All City Plumbing, Air & Electrical backflow testing
4 mi

All City Plumbing, Air & Electrical

No reviews yet

Rancho Cucamonga, CA · 4 mi

Preventer RepairCommercial
Website
Backflow Parts USA backflow testing
4 mi

Backflow Parts USA

4.8(9)

Rancho Cucamonga, CA · 4 mi

Website
First Class Plumbing & AC backflow testing
5 mi

First Class Plumbing & AC

No reviews yet

Rancho Cucamonga, CA · 5 mi

CommercialEmergency Service
Website
Mr. Rooter Plumbing of The Inland Empire backflow testing
11 mi

Mr. Rooter Plumbing of The Inland Empire

4.8(589)

Fontana, CA · 11 mi

Backflow Testing

I recently had a shower valve body replacement done by Hector from Mr. Rooter, and the experience was outstanding. The original valve was seized, and a simple cartridge replacement wasn’t possible…

Read more on Google
Website
Amazing Force Plumbing & Backflow LLC backflow testing
13 mi

Amazing Force Plumbing & Backflow LLC

5.0(322)

Corona, CA · 13 mi

Backflow TestingPreventer InstallationPreventer Repair

Where do I begin......... Amazing Force Plumbing has provided excellent service for my rental properties as well as my home for the last several years. Kenneth is the owner and he takes pride in…

Read more on Google
Website
Hydro Backflow backflow testing
14 mi

Hydro Backflow

5.0(2)

West Covina, CA · 14 mi

Annual Certification FilingCommercialResidential
Website
E.R. Block Plumbing Inc. backflow testing
14 mi

E.R. Block Plumbing Inc.

No reviews yet

Riverside, CA · 14 mi

Preventer InstallationPreventer RepairCommercial
Website
Southern California Backflow backflow testing
Testing Verified
14 mi

Southern California Backflow

5.0(5)

Testing Verified · Riverside, CA · 14 mi

Backflow TestingPreventer InstallationPreventer Repair
Website
Campbell Family Plumbing & Electric backflow testing
16 mi

Campbell Family Plumbing & Electric

4.9(87)

Riverside, CA · 16 mi

CommercialEmergency ServiceSame Day Service
Website
Jim & Sons Plumbing & Rooter backflow testing
Testing Verified
16 mi

Jim & Sons Plumbing & Rooter

5.0(760)

Testing Verified · Riverside, CA · 16 mi

Backflow TestingCommercialEmergency Service
Website
Righty Tighty Plumbing Inc. backflow testing
16 mi

Righty Tighty Plumbing Inc.

No reviews yet

Riverside, CA · 16 mi

CommercialResidential
Website
First Class Plumbing & AC backflow testing
16 mi

First Class Plumbing & AC

4.9(810)

Riverside, CA · 16 mi

CommercialEmergency Service
Website
Pro Backflow Testing Services backflow testing
Testing Verified
16 mi

Pro Backflow Testing Services

5.0(4)

Testing Verified · Rialto, CA · 16 mi

Backflow Testing
Website
All City Plumbing, Air & Electrical backflow testing
16 mi

All City Plumbing, Air & Electrical

5.0(1,900)

Anaheim, CA · 16 mi

Preventer RepairCommercial
Website
NIR Plumbing & Air Conditioning backflow testing
Testing Verified
16 mi

NIR Plumbing & Air Conditioning

4.8(161)

Testing Verified · Riverside, CA · 16 mi

Backflow Testing
Website
Rossman Plumbing backflow testing
17 mi

Rossman Plumbing

4.7(148)

Riverside, CA · 17 mi

Emergency Service
Website
Roto-Rooter Plumbing & Water Cleanup backflow testing
17 mi

Roto-Rooter Plumbing & Water Cleanup

No reviews yet

Riverside, CA · 17 mi

CommercialResidentialEmergency Service
Website
Ferguson Waterworks backflow testing
18 mi

Ferguson Waterworks

No reviews yet

Riverside, CA · 18 mi

ResidentialEmergency ServiceFree Estimates
Website
Mr. Rooter Plumbing of San Bernardino backflow testing
18 mi

Mr. Rooter Plumbing of San Bernardino

4.8(1,356)

Colton, CA · 18 mi

Backflow Testing

Our 20+ year old water heater died on us and had to be immediately replaced. I contacted at least 7 plumbing companies and Mr. Rooter was the only one who had same day availability. Also, the rep…

Read more on Google
Website
Los Angeles Plumbing & Backflow backflow testing
Testing Verified
20 mi

Los Angeles Plumbing & Backflow

5.0(3)

Testing Verified · Irwindale, CA · 20 mi

Backflow TestingPreventer InstallationPreventer Repair
Website

Frequently Asked Questions About Backflow Testing in Ontario

Backflow testing in Ontario, California typically costs between $50 and $200 per device, depending on the type of backflow preventer and the complexity of the installation. RPZ assemblies generally cost more to test than double check valve assemblies. Contact providers listed above for current pricing in the Ontario area.

If a backflow preventer fails its annual test, the certified tester will diagnose the issue — often a worn check valve, damaged disc, or fouled relief valve. Most testers in Ontario can repair the device on site and re-test it the same day. Your water authority may require the passing report within a set deadline.

Cross-connection control prevents contaminated water from flowing backwards into the clean water supply. Backflow prevention devices are installed at cross-connection points to protect public health. Regular testing ensures these devices function properly. Many municipalities in California require cross-connection control programs for commercial properties and irrigation systems.

Many municipalities in California require annual backflow testing for commercial and residential properties with backflow prevention devices. Your local water authority in Ontario can confirm the exact testing schedule and deadlines for your area. Failing to test on time may result in fines or water service interruption.

Some certified testers near Ontario offer same-day or emergency scheduling for urgent situations such as a failed device, a compliance deadline, or a new construction inspection. Check individual provider listings above for availability, or request a quote to find a tester who can accommodate your schedule.

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