Backflow Testing in San Jose: Who Does It Depends on Your Water Company
Ask three San Jose homeowners who tests their backflow preventer and you can get three different answers, and all three can be right. That’s because San Jose doesn’t have one water company. Depending on where you live, your water comes from San Jose Water, the City’s own San José Municipal Water System, or Great Oaks Water Company, and each one handles backflow testing its own way.
So before you book anything, it’s worth finding out which company you’re dealing with.
Step one: look at your water bill
The name at the top of your water bill tells you everything. Your ZIP code alone doesn’t always settle it, because the three service areas don’t follow ZIP code lines neatly.
Once you know the company, the rest is straightforward.
San Jose Water: they test it for you
San Jose Water serves most of the city, along with Campbell, Los Gatos and Saratoga. If that’s your supplier, here’s the good news: San Jose Water performs the testing itself, at no charge to its customers. You don’t hire a tester for the annual test.
What you still own is the device. San Jose Water requires testing and recordkeeping on every backflow preventer at least once a year, and its rules for what can be installed are fairly strict. It requires a reduced pressure (RP) assembly under most conditions, and a double check assembly needs its approval first. Systems with pumps need an air gap. Any new assembly has to be lead-free, and it has to appear on the USC Foundation’s list of approved assemblies. San Jose Water also suggests checking with its Backflow Department before you buy one, because not every listed model meets its requirements.
If San Jose Water’s test finds a problem, the device has to be repaired or replaced. That part is on you, and it’s where we come in for San Jose Water customers: minor repairs to get a failed device passing again.
San José Municipal Water: you hire the tester
Muni Water serves parts of North San Jose, Evergreen, Alviso and Coyote Valley. Its rules are the opposite of San Jose Water’s. The City says plainly on its backflow FAQ that Muni Water does not test customers’ backflow assemblies. Testing and maintenance are the responsibility of the account holder or property owner, who must hire a third-party backflow tester certified by the American Water Works Association.
Muni Water also recommends putting hose bib vacuum breakers on all your hose bibs. They’re inexpensive, you can buy them at most hardware stores, and they protect your own plumbing from a hose left in a bucket or a pool. They don’t replace a testable assembly where one is required, though.
Great Oaks Water: you hire a registered tester
Great Oaks Water serves much of south San Jose. Its cross-connection program is run for it by an outside company, BSI Online, and the Great Oaks backflow page links to a lookup where you can find a registered testing company or check the status of a test. As with Muni Water, you arrange the test yourself. Questions about the program go to Great Oaks directly at backflow@greatoakswater.com.
Why the device needs a yearly test at all
Whichever company you have, the reason for the annual test is the same. A backflow preventer is a set of spring-loaded check valves that close if water tries to run backward from your property into the public main. That can happen when pressure in the main drops suddenly, say during a main break or when the fire department opens hydrants nearby.
The rubber seals and springs inside those valves wear out, and debris from the main can lodge on a valve seat and keep it from closing. None of that shows from the outside. A device that’s quietly failed looks exactly like one that’s working, which is why a tester has to put a gauge on it once a year.
What a test is like
If you’re a Muni Water or Great Oaks customer, the visit itself is quick. The tester shuts off water at the assembly for a short time, connects a calibrated gauge to the test ports and checks that each valve holds. Most residential devices are outside, so as long as the tester can get to it, you don’t need to be home. If the device sits in a locked cage, leave a key or the combination.
If it passes, the results go to your water company and you’re done for the year. If it fails, the usual fix is a repair kit with new rubber parts, followed by a retest. A device that’s cracked, frozen or too old to get parts for has to be replaced, which is work for a licensed plumbing contractor and usually needs a permit.
The short version
Check your water bill. If it says San Jose Water, they’ll test the device; call someone if it fails. If it says San José Municipal Water or Great Oaks Water, the annual test is yours to arrange with a certified tester.
For Muni Water and Great Oaks customers, a BackflowCare test is $199 per device, and we file the results with your water company. You can book online or read more on our San Jose page.
Common questions
Do I need to hire a backflow tester in San Jose?
It depends on your water company. San Jose Water tests its customers' backflow devices itself at no charge. San José Municipal Water and Great Oaks Water customers arrange the annual test themselves.
How do I know which water company serves my San Jose home?
Look at your water bill. San Jose has three water companies: San Jose Water, the City's San José Municipal Water System and Great Oaks Water Company. ZIP codes don't line up neatly with their service areas.
Who pays to repair a failed backflow device in San Jose?
The property owner. Even where San Jose Water does the test, a device that fails has to be repaired or replaced by the owner.
What kind of backflow preventer does San Jose Water require?
San Jose Water requires a reduced pressure (RP) assembly under most conditions. A double check assembly needs its approval first, and new assemblies must be lead-free and on the USC approved list.