Assembly fails every year
Debris on the check seats, usually from work upstream on the main. A rebuild kit is inexpensive, but repeated failures mean the assembly is worn out and replacement is cheaper over three years.
Plumbing & Drains16724 businesses listed
Backflow prevention testing and repair
If your premises has an irrigation system, a boiler, a carbonator, a dish machine, a fire line or almost any commercial water connection, the water utility requires a backflow prevention assembly and an annual test by a certified tester. Work covers the test itself, repair or rebuild where the assembly fails, replacement, and filing the report with the utility. Missing the test is one of the few maintenance items where the penalty is having your water shut off.
Enter your ZIP to see the businesses listed for this trade nearest to your site, with their phone numbers.
- Free to searchno account, nothing to submit
- Public registersevery listing names its source
- License numberswhere the state publishes one
- Directyou call the business yourself
- Our estimate
- $120-$2,400
- Time on site
- 0.75-5 hrs
- Fault patterns covered
- 2
- Businesses listed
- 16724
What backflow prevention testing and repair costs
Most of these jobs land near $260. The full spread runs $120 to $2,400, and the gap between those two ends is diagnosis against replacement rather than one business being dearer than another.
What moves it: how much of the job is parts, whether the fault is found in the first hour or the third, access to the equipment, and the hour of the day you call. We never speak to the businesses listed here, so there is no rate card behind any of this. It is our own band for the category, and there is no regional index: the figure does not change with your metro.
| How soon you need it | Typical | Range |
|---|---|---|
| Scheduled visitBooked in advance, no urgency multiplier applied | $260 | $120 to $2,400 |
| Same dayOur band multiplied by 1.12 | $290 | $135 to $2,690 |
| Emergency calloutOur band multiplied by 1.35 | $350 | $160 to $3,240 |
Our estimate from national cost bands, not a quote from any business. Every row is the same band with the urgency multiplier the site applies everywhere else, so this table can never contradict the headline number. Ask for a written price before the work starts.
Who is licensed to do this work
In California the classification that squarely covers this is C-36 plumbing, and the register says who holds it. Every listing on this site shows the classification, the license number and the date we read it, with a link back to the register entry so you can check it against the state rather than against us.
Overlapping classifications exist and are labeled as overlapping rather than as a match: C-42 sanitation system and C-55 water conditioning. A general building contractor may hold the job and subcontract the trade, which is a real answer and a different one, so the card says which of the two you are looking at.
One thing worth being plain about: CSLB classifications do not distinguish commercial work from residential. There is no separate commercial license to hold and no register field that would prove one. That is why this page describes the equipment rather than the contractor, and why nothing here says a business has been checked out. We read a public record on a stated date. That is the whole claim.
Before you pay for a callout
Two minutes of checks that sometimes end the problem
We would rather you did not need a callout at all. These are the checks that end the most calls for this fault.
Try a quick fix first
Some issues resolve without a truck roll. Two minutes now can save the callout.
- 1
Find the notice from your water utility. It names the assembly, the deadline and often the testers the utility accepts, which narrows your search immediately.
- 2
Check the tester is certified for your utility specifically, not only licensed. Certification is per-agency in much of California and an uncertified test does not count.
- 3
Locate the assembly before the visit. They are frequently behind a locked gate, under a bush or inside a vault nobody has opened in a year.
- 4
Ask for the filed report, not just an invoice. The utility wants the report and you want a copy of what was submitted.
What the visit actually includes
- Test of each assembly to the utility's accepted procedure
- Repair kit or rebuild where an assembly fails
- Retest after any repair
- Report filed with the water utility
- Copy of the certificate for your own file
Diagnosis
How backflow faults usually present
Written from how these faults actually present on a working premises, not from a manual.
Nobody can find the assembly
Common in a leased unit that changed hands. The utility knows where it is, because they have it on record as your responsibility.
Listed for this trade
Businesses listed for backflow
Read from public license registers, so there is no ranking here and no distance: this page has no location to measure from. Enter your ZIP to sort by who is nearest to your site.
By location
Backflow prevention testing and repair near you
Local pages show which businesses are listed for that metro, how far out they sit, and the local conditions that drive demand.
| Metro | Businesses listed |
|---|---|
| Backflow in Los Angeles, CA | 4207 |
| Backflow in San Diego, CA | 976 |
| Backflow in Sacramento, CA | 790 |
| Backflow in Fresno, CA | 194 |
| Backflow in San Jose, CA | 842 |
Counted from the businesses we have imported for each metro center inside a 25 mile radius. A metro reads “none yet” until we load a register that covers this trade there.
All coverage areasQuestions owners ask
Backflow FAQs
Short, specific answers. If yours is not here, ask the business you call before you agree to the visit.
How often is testing required?
Annually in most jurisdictions, and after any repair or relocation. Your water utility sets the interval and the deadline, and they are the ones who send the notice.
What happens if I miss it?
Most utilities escalate from a reminder to a fine and eventually to disconnection, because an untested assembly is a contamination risk to the public main. It is the deadline worth putting in the calendar.
Who can test?
A certified backflow tester whose certification your utility accepts. Many also hold a C-36 plumbing license, which the listings here show from the state register.
Related work
Often booked in the same visit
Batching jobs into one mobilization is the cheapest way to buy this kind of work.
Water heaterNo hot water, lukewarm supply, leaking tanks, pilot faults and tankless error codes.from $220Commercial drainSlow and backed-up sinks, floor drains, toilets and the line under the kitchen.from $180Water leakBurst pipes, ceiling drips, running meters and leaks you can hear but not see.from $240RestroomRunning toilets, blocked pans, failed flush valves, taps, urinals and sink wastes.from $170
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Ready when you are
Need backflow sorted?
Search your ZIP to see the businesses listed for this trade nearest to your site, with the license numbers and phone numbers we hold, then call them yourself.
- Cost to search
- Free
- Account needed
- None
- Who you call
- The business