San Diego DMA · the assembly on the line
What a backflow preventer is
A backflow preventer is a plumbing assembly that stops water from reversing into the potable supply. Irrigation, fire lines, and many commercial buildings in San Diego County have one because fertilizer, standing water, or building pressure should not enter the public main. The device is why you get a test notice. This page defines it. It does not replace the utility.
Why the device exists
Water normally flows one way. A pressure drop on the street side — a main break, hydrant use, or a pump — can reverse flow. The preventer is the mechanical answer to that hazard. Cross-connection programs exist so that reversal does not reach neighbors.
What backflow testing is is the next explainer when the notice is already in your hand.
RPZ, double-check, and PVB
An RPZ valve is the high-protection assembly with a relief port — common on commercial, some irrigation, and fire lines. A double-check is a simpler pair of checks. A pressure vacuum breaker sits higher on some smaller irrigation systems.
The tag on the device is better than a guess. RPZ testing and annual testing are the request pages once you know you need a certified test.
Where they hide in this county
Behind a hedge, in a green cage, in a mechanical room, in a vault at the parkway. La Mesa and older commercial pads hide them in tight side yards. HOA landscapes have several cages. Write what you can see from the sidewalk. If you cannot find it, say that.
Do not send lockbox combinations. Write “needs access.”
What this page will not do
It will not assign a hazard class, pick a device size, or file with your district. City of San Diego is not Chula Vista, Escondido, or an East County district. Name the agency on the letter.
A certified local tester may contact you if they accept the lead. If you already have a tester who files every year, stay with them.
Related service requests
These are narrower request pages on this site, not a list of partner shops. A licensed local provider may contact you if they accept a lead.
Local statistics
San Diego backflow testing statistics, 2026 — public-record figures, not a bid from San Diego Backflow Testing.
Questions
Is a backflow preventer the same as a shutoff valve?
No. It has shutoffs on it, but its job is to stop reverse flow, not only to turn water off. Do not treat it as a garden valve.
Do houses have them, or only businesses?
Both. Irrigation and some fire or domestic services on houses and HOAs carry assemblies. Commercial properties are the other common notice. Follow the letter you received.
Can I test it myself?
Not for the agency. California testers hold specific certification. This website does not. Ask to see a current card before anyone opens the device.
Is this a plumbing emergency page?
No. If a pipe is broken or water is off, call a plumber directly. This form is for scheduled testing and failed-test repair.
Related pages
These are more request pages on this site, not a list of partner shops. A licensed local provider may contact you if they accept a lead.
Request backflow testing in San Diego
Call if you want to talk now, or send the form. Either way this is a request, not a booked job.
Call (619) 604-7252