Backflow prevention testing and repair in San Jose
A backflow assembly keeps irrigation and process water out of the drinking supply, and it has to prove that once a year.
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Perfect Tankless Plumbing, San Jose, CA
Backflow testing in San Jose checks that an assembly, such as a reduced pressure principle or double check valve, still stops contaminated water from flowing back into the public supply; tests are typically annual, failed devices are repaired or rebuilt, and results are submitted to the water purveyor.
Updated September 2026
Repipe, Gas & Water Quality
What a backflow assembly protects
Backflow happens when pressure in the public main drops, or pressure on the property side rises, and water flows the wrong way. Irrigation systems, boilers, fire sprinklers and commercial equipment can push fertilizer, chemicals or stagnant water back toward the drinking supply.
Backflow assemblies stop that, and because their checks and relief valves wear out, water purveyors require them to be tested on a schedule, usually yearly.
Included
What a backflow test includes
- Assembly located and identified
- Calibrated test gauge
- Check valve tightness readings
- Relief valve test on RP assemblies
- Repair with manufacturer parts if failed
- Retest after repair
- Results submitted and copied to you
Annual test
An annual test uses a calibrated differential pressure gauge connected to the assembly's test cocks. We close the shutoffs in sequence and check that each check valve holds and, on a reduced pressure assembly, that the relief valve opens at the right point. The test takes a short time with water off only to the protected system. Passing results are recorded and submitted to the water purveyor, and you receive a copy for your records along with the date the next test is due.
Device repair
When an assembly fails, the cause is usually debris on a check seat, a worn rubber part, or a stuck relief valve. We shut it down, disassemble it, clean or replace seats, springs, discs and seals from the manufacturer's repair kit, reassemble and retest. Most failures are repaired on the same visit. Assemblies that are obsolete, seized solid or damaged beyond repair are replaced with an approved model of the right type for the hazard, and then tested before the system goes back into service.
Irrigation backflow
Home and commercial irrigation systems are the most common backflow hazard because they connect drinking water to soil, fertilizer and standing water in sprinkler lines. We test and repair irrigation assemblies, check that they are installed at the right height and orientation, and replace atmospheric vacuum breakers or pressure vacuum breakers that have failed. An irrigation assembly left untested for years can put a neighborhood's drinking water at risk during a pressure drop, which is exactly why the annual test exists and why purveyors enforce it.
Local context
Irrigation and dry summers in San Jose
San Jose's long dry season means irrigation systems run for months, and the backflow assemblies protecting them work hard the whole time. An assembly that sat through winter with debris in a check seat often fails its first test of the year. We suggest scheduling the annual test in spring, before watering starts in earnest, so any repair is finished before the system is running every day and the landscape depends on it.
How the job runs
How a backflow visit runs
- 1
Locate the assembly
And confirm its type and size.
- 2
Test
Calibrated gauge on the test cocks.
- 3
Record
Pass or fail readings.
- 4
Repair if needed
Seats, springs and seals from the kit.
- 5
Retest
Confirm it now passes.
- 6
Submit
Results to the water purveyor, copy to you.
Options
Common backflow devices
| Reduced pressure (RP) | Double check (DCVA) | Pressure vacuum breaker (PVB) | |
|---|---|---|---|
| Hazard level | High | Low to moderate | Irrigation |
| Relief valve | Yes, discharges water | No | Air inlet |
| Common use | Commercial and chemical systems | Fire lines and some commercial | Lawn sprinklers |
| Install height | Above grade | Above or below grade | Above the highest head |
| Testable | Yes | Yes | Yes |
| Typical failure | Relief valve or check | Check seat | Poppet or check |
Cost factors
What backflow service costs depend on
We do not publish a local backflow price; the device type and whether it passes set the cost.
- Assembly type. RP, double check or vacuum breaker
- Pass or fail. repairs add parts and time
- Size. larger commercial assemblies take longer
- Access. enclosures and below-grade vaults
- Replacement. for obsolete or damaged devices
- Paperwork. submitting results to the purveyor
FAQ
Backflow Testing and Repair questions from San Jose homeowners
Usually once a year, as required by the water purveyor.
We repair it with manufacturer parts and retest, usually the same visit.
Homes with irrigation or other protected systems often do.
Yes. Results go to the water purveyor and you get a copy.
Yes, with an approved assembly suited to the hazard.
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Schedule your backflow test
Call to book the annual test or a repair. We handle the gauge work and the paperwork.
