Why Irrigation Assemblies Require Testing
Irrigation assemblies require testing because internal checks, springs, seals, air inlets, and relief valves can wear or collect debris without obvious exterior damage. A device may look dry and intact while failing to hold the required pressure differential.
Irrigation creates a potential cross-connection between potable water and piping exposed to soil, fertilizers, animal waste, and standing landscape water. Back-siphonage or backpressure can reverse normal flow when water-system pressure changes. The approved assembly creates a tested barrier appropriate to the installation.
Seattle Public Utilities requires installed mechanical backflow assemblies to receive annual testing by a Washington State certified Backflow Assembly Tester. Testing is also required after repair or replacement.
What a Certified Backflow Test Checks
A certified backflow test checks the performance of the specific assembly type. The tester identifies the make, model, size, serial number, and location, then uses a calibrated differential-pressure test kit and the approved procedure for that assembly.
Depending on the equipment, testing evaluates:
- Check-valve holding pressure
- Air-inlet opening on a pressure vacuum breaker
- First and second checks in a double check valve assembly
- Relief-valve opening and check performance in a reduced pressure assembly
- Shutoff-valve operation
- Test-cock condition and leakage
- Evidence of freeze damage, corrosion, or incorrect installation
Water service to the irrigation line is interrupted during the field test. The time required depends on accessibility, assembly condition, and whether repairs are necessary.
Passing, Failing, Repair, and Retesting
Passing, failing, repair, and retesting follow measured results. A passing assembly meets the required field-test criteria at the time of service. The tester records the readings and assembly details for the official report.
A failed result identifies which component does not meet the standard. Common causes include debris on a check seat, worn rubber parts, weak springs, a failed air inlet, leaking shutoff valves, or freeze damage. Service may involve cleaning, installing model-specific repair parts, or replacing a cracked or obsolete assembly.
The assembly must be retested after repair or replacement. Returning water to the irrigation system without a passing post-repair test does not confirm that cross-connection protection has been restored.
Seattle Annual Testing and Report Submission
Seattle annual testing and report submission remain the property owner's responsibility even when SPU sends a reminder. A Washington State certified Backflow Assembly Tester performs the test and submits the result directly to Seattle Public Utilities.
SPU moved backflow test reporting to its SAMS Tester Portal in August 2026 and stopped accepting test reports through the former email inbox. Testing companies and testers maintain their credentials and calibrated test-kit information in that system. Property owners should request documentation for their records and confirm that the result was submitted.
New assemblies must be installed in an approved manner and tested before being placed in service. SPU determines the type of protection required for the specific installation and hazard.
Preparing the Assembly for Service
Preparing the assembly for service makes testing safer and more efficient. Clear plants, stored items, soil, and standing water from the device. Make sure the tester can reach the shutoff valves, test cocks, identification tag, and discharge area.
Do not paint over the nameplate, bury an above-ground assembly, plug a relief opening, or operate frozen components. Tell us about recent leaks, repairs, winter damage, chemical injection, or changes to the irrigation connection because those details can affect the required protection and service plan.
Frequently Asked Questions
How often does Seattle require irrigation backflow testing?
Seattle Public Utilities requires annual testing of installed mechanical backflow assemblies by a Washington State certified Backflow Assembly Tester.
Does a visual inspection count as the annual test?
No. A certified field test uses calibrated equipment to measure internal performance. Appearance alone cannot confirm that check valves or relief components meet the required criteria.
What happens if the assembly fails?
The failed component is diagnosed, repaired or replaced as appropriate, and the assembly is tested again. A passing post-repair result confirms performance.
Who sends the test result to Seattle Public Utilities?
The certified tester submits the result directly through SPU's current reporting system. The property owner should retain documentation and confirm submission.
Schedule Irrigation Backflow Testing in Seattle
Schedule Irrigation Backflow Testing with Seattle Plumbers for certified field verification, clear results, and repair coordination when needed. We help move the assembly from due status to documented testing through Seattle's current process.