How Much Does a Backflow Test Cost in California? What Drives the Price
Backflow test cost in California depends on assembly type and size, how many you have, access, repairs, and water supplier fees. How each factor works.
Short answer: A backflow test in California is priced per assembly, and the total depends mostly on the type and size of each assembly, how many you have, how easy they are to reach, and whether anything fails and needs repair and a retest. Los Angeles County Waterworks Districts tells its customers a test is “usually between $75–$150 per device,” while noting the cost varies by tester and location (LA County Public Works). Quotes elsewhere in the state can fall outside that range, so compare quotes from certified testers using the factors below.
Exodus Water Services does not publish a price list. Every property is quoted on its own assemblies. This guide explains what you are paying for, so you can compare quotes on equal terms and avoid surprise costs.
Why every California property with an assembly pays for a test
Under the State Water Board’s Cross-Connection Control Policy Handbook (CCCPH), every backflow prevention assembly installed for a water system’s cross-connection control program must be field tested at least annually, and also after installation, repair, depressurization for winterizing, or permanent relocation (CCCPH 3.3.3(a) and (b)). The test must be performed by a certified backflow prevention assembly tester (CCCPH 3.3.3(a)).
The California Plumbing Code puts the same duty on the property side: the “premise owner or responsible person” must have the assembly tested by a certified backflow assembly tester at installation, repair, or relocation, and at least annually after that (2025 California Plumbing Code 603.4.2). That is why the cost lands on the owner or account holder, not the water company. For the full rules, see our guide to backflow testing in California.
The six factors that set the price
| Cost factor | Why it changes the price |
|---|---|
| Assembly type | Each type has its own field test procedure. An RP has two checks and a relief valve to verify; a PVB has one check and an air inlet valve. |
| Assembly size | Larger assemblies, often on fire lines or commercial services, take more setup and time. |
| Number of assemblies | Each assembly is tested and reported separately. Several at one site usually share one trip. |
| Access | Buried, boxed, elevated, or locked assemblies take longer to reach and test safely. |
| Repairs and retests | A failed assembly must be repaired or replaced within 30 days and then retested. |
| Water supplier fees and filing | Some suppliers set their own fees or require reports through an online portal. |
1. Assembly type
California recognizes several types of testable assemblies: the reduced pressure principle assembly (RP), double check valve assembly (DC), pressure vacuum breaker (PVB), spill-resistant vacuum breaker (SVB), and the detector versions used on fire lines (RPDA and DCDA). The handbook requires certified testers to know the field test procedure for each of these types (CCCPH 3.4.1(b)(1)(B)(4)).
The procedures are not the same length. An RP has two independently acting check valves plus a differential pressure relief valve between them (CCCPH 3.1.1), and the tester has to verify each part. A PVB or SVB has a single check valve and an air inlet valve. A detector assembly adds a bypass with its own meter and a second, smaller assembly (CCCPH 3.1.1). More components to verify generally means more time on site. Our guide to the types of backflow preventers explains each one.
An air gap is not a mechanical assembly, so it is not field tested with gauges. It must be visually inspected at least annually by a certified tester or a certified cross-connection control specialist (CCCPH 3.3.3(c)). See air gap backflow prevention.
2. Assembly size
Residential irrigation assemblies are often small. Commercial domestic services and fire sprinkler lines use larger assemblies, and fire lines often use detector assemblies with a bypass meter. Larger valves can take longer to isolate, test, and restore, and some testers price them separately.
3. Number of assemblies
You pay for each assembly, because each one gets its own test and its own report. Water suppliers keep separate records for each assembly, including its location, type, manufacturer, model, size, and serial number (CCCPH 3.5.1(a)(2)). A property with a domestic service assembly, an irrigation assembly, and a fire line assembly has three tests to schedule.
If you manage several assemblies at one site, or several sites in one area, ask whether the tester can schedule them on the same day. Fewer trips usually means a lower total.
4. Access
The CCCPH requires every assembly and air gap to be accessible for field testing, inspection, and maintenance (CCCPH 3.3.2(h)). New installations have clearance rules: an RP must sit at least 12 inches above grade, and an RP or DC installed after the handbook was adopted needs at least 12 inches of side clearance and 24 inches on the test cock side, unless the water system approves something else (CCCPH 3.3.2(b) and (f)).
Older installations do not always meet these standards. An assembly in a flooded box, behind a locked gate, inside a mechanical room that needs an escort, or high on a wall takes longer to test. Tell the tester about access problems up front so the quote reflects them.
5. Repairs and retests
This is the factor that changes the total the most. If an assembly fails, it must be repaired or replaced within 30 days of the notice of failure, and the repaired assembly must be field tested again (CCCPH 3.3.3(a) and (e)). So a failure adds:
- Parts and labor for the repair, or the cost of a replacement assembly.
- A retest after the repair, by a certified tester.
- Possible upgrade costs. A replacement must be an approved assembly (CCCPH 3.3.1(b)), and if your property is high hazard, a new or replacement assembly installed after July 1, 2024, must be an air gap or an RP, not a DC (CCCPH Appendix D).
Ask every tester how they handle failures: whether they repair, who they refer repairs to, and whether the retest is priced separately. See what happens if a backflow test fails.
6. Water supplier fees and report filing
Each water system runs its own cross-connection control program under rules or ordinances it adopts (CCCPH 3.1.3(a)(1)). Those local rules decide how test reports are submitted and whether the supplier charges any fee of its own. Some suppliers ask testers to file results through an online portal. For example, testers working in Ventura County Waterworks Districts 1, 17, 19, and 38 must enroll in SwiftComply and submit results electronically (Ventura County Public Works).
Check your test notice or your supplier’s fee schedule before you book. If a fee applies, ask the tester whether it is included in the quote.
Costs you can avoid
The most expensive outcomes are the ones that come from waiting:
- Missing the deadline. Every water system must have legal authority to act when a customer does not test or maintain a required assembly. Options include denying or discontinuing service, or installing, testing, or maintaining the assembly itself (CCCPH 3.1.3(a)(1)). LA County Waterworks Districts, for example, issues a shut-off notice when a test is not arranged by the due date and may terminate service until the assembly is tested (LA County Public Works).
- Letting a failure sit. The 30-day repair window starts at notification of the failure (CCCPH 3.3.3(e)).
- Modifying an assembly. Approved assemblies must not be modified, and water systems must require testers to report modified assemblies (CCCPH 3.3.1(c)). A modified assembly may have to be replaced.
How to compare backflow test quotes
Ask each tester the same questions:
- Is your certification current, and from which organization? Since July 1, 2026, certification must come from an organization the State Water Board recognizes. See how to become a certified backflow tester.
- Is the price per assembly, and does it change by type or size?
- Does the price include filing the report with my water supplier?
- What happens if an assembly fails? Who repairs it, and what does the retest cost?
- Can you test all my assemblies in one visit?
- Will I get a copy of each test report? Water suppliers keep results for three calendar years (CCCPH 3.5.1(a)(4)), but you should keep your own.
A lower quote that leaves out filing, retests, or access time can cost more in the end.
How Exodus Water Services prices backflow testing
Exodus Water Services is based in Thousand Oaks. Our certified backflow prevention assembly testers test RP assemblies, double check valve assemblies, pressure vacuum breakers, spill-resistant vacuum breakers, and air gaps. We quote each property on its own assemblies, access, and water supplier requirements. When an assembly fails, we coordinate the repair with a licensed contractor and retest it. Water systems that need help running a whole program can see our cross-connection control programs.
Frequently asked questions
How much does a backflow test cost in California? It depends on the assembly type, size, number of assemblies, access, and any repairs. Los Angeles County Waterworks Districts tells customers a test is usually between $75 and $150 per device, and notes that cost varies by tester and location.
Why does an RP cost more to test than a vacuum breaker? An RP has two check valves and a differential pressure relief valve, and each must be verified during the field test. A PVB or SVB has one check valve and an air inlet valve, so there is less to test.
Who pays for the backflow test, the owner or the water company? Usually the owner or account holder. The California Plumbing Code makes the premise owner or responsible person responsible for having the assembly tested (CPC 603.4.2), and the water system enforces testing through its program.
Does a failed backflow test cost extra? Usually, yes. A failed assembly must be repaired or replaced within 30 days and then retested (CCCPH 3.3.3(a) and (e)), so you pay for parts, labor, and a second test.
Is there a fee to file the test report with my water supplier? It depends on your supplier. Each water system sets its own program rules. Check your test notice or the supplier’s fee schedule, and ask your tester whether filing is included in the quote.
Is it cheaper to test several backflow assemblies at once? Often. Each assembly is still tested and reported separately, but scheduling them in one visit can reduce trip and setup time. Ask your tester how multi-assembly visits are priced.
Does an air gap need a paid backflow test? An air gap is visually inspected rather than tested with gauges. The CCCPH requires an annual inspection by a certified tester or cross-connection control specialist (CCCPH 3.3.3(c)).
Last reviewed: October 30, 2026.
Sources
- State Water Board, Cross-Connection Control Policy Handbook, April 2026 revision (PDF): sections 3.1.1, 3.1.3, 3.3.1, 3.3.2, 3.3.3, 3.4.1, 3.5.1, and Appendix D
- State Water Board, Cross-Connection Control Policy Handbook page
- IAPMO, 2025 California Plumbing Code (read-only edition): section 603.4.2
- Los Angeles County Public Works, Waterworks Districts backflow prevention
- Ventura County Public Works, Cross-connection and backflow
Need a quote for your assemblies? Call (805) 991-7333 or request a review.