Washington · statewide
Backflow testing in Washington: the annual test and certified testers
Updated · Prepared by the Plumb Right Now editorial team
Signs Washington homeowners call about: A test notice from your water provider, a failed test, a dripping assembly
Short answer
Under WAC 246-290-490, backflow assemblies that protect a Washington public water system must be inspected and tested when installed, repaired, reinstalled or relocated, and at least once a year after that. The tests are done by a Backflow Assembly Tester (BAT) certified by the state, and each water purveyor runs its own cross-connection program, tracking test reports and tester certifications.
What Washington requires or changes
Approved backflow assemblies protecting the public water system are inspected and tested on installation, repair, reinstallation or relocation, and annually thereafter; a purveyor may require more frequent testing for high-hazard premises or assemblies that repeatedly fail. [1]
A Backflow Assembly Tester (BAT) is a person holding a valid BAT certificate issued under chapter 246-292 WAC. [1]
Purveyors must eliminate or control cross-connections between their system and a customer's plumbing with an approved backflow preventer suited to the degree of hazard. [1]
Each purveyor runs a testing quality-control program covering tester certification, test kit calibration, test report contents and deadlines for submitting reports. [1]
What this means at home
Most homeowners meet the rule through a lawn irrigation backflow assembly, a fire sprinkler connection or a boiler feed. Your water utility sends the annual reminder; you hire a certified BAT, and the tester files the report with the utility. See Seattle and Spokane for local context and backflow testing for how a test works.
Before you hire a tester
- Ask for the tester's Washington BAT certificate number.
- Confirm the tester's test kit has a current calibration, which purveyors track.
- Ask whether the tester submits the report to your purveyor and by when.
Common questions
How often are backflow assemblies tested in Washington?
On installation, after repair, reinstallation or relocation, and at least once a year after that.
Who can test a backflow assembly in Washington?
A Backflow Assembly Tester holding a valid state BAT certificate under chapter 246-292 WAC.
Can a Washington utility require testing more than once a year?
Yes, for high-hazard premises or assemblies that repeatedly fail.
Which Washington rule covers backflow testing?
WAC 246-290-490, the state cross-connection control rule for public water systems.
Do I need a new test after moving a backflow assembly in Washington?
Yes. Relocation and reinstallation both trigger a test.
Why does my Washington sprinkler system need a backflow test?
Irrigation lines can pull fertilizer and soil water back into the drinking water, so utilities require an approved assembly and a yearly test.
Who decides what backflow preventer a Washington home needs?
The water purveyor, based on the degree of hazard of the connection.
Does a Washington tester's equipment need calibration?
Yes. Purveyors track test kit calibration as part of their quality-control programs.
Who sends the backflow test report to my Washington utility?
Usually the tester, within the purveyor's deadline; confirm before the test.
What happens if I skip my Washington backflow test?
Purveyors enforce their programs and can take action, including shutting off service to an unprotected connection.
Backflow Testing across Washington
- Backflow Testing in SeattleSeattle Public Utilities backflow testing rules: annual tests by your anniversary date, Washington-certified testers, reporting, and non-compliance charges.
- Backflow Testing: the full guideWhat backflow is, which homes and businesses need backflow preventers, how annual backflow testing works, and what happens if a device fails.
- Plumbing in WashingtonWashington's plumbing code, licensing, climate and the cities we cover.
The same service in other states
- Backflow testing in California: the state cross-connection rulesCalifornia backflow testing under the State Water Board's cross-connection handbook: in effect since July 2024, annual tests, and what homes need.
- Backflow testing in Texas: TCEQ licensing and the annual testBackflow testing in Texas: the TCEQ tester license anyone testing or repairing assemblies must hold, test-at-install and annual rules, and gauge accuracy checks.
- Backflow testing in Oregon: OHA-certified testersWho can test backflow assemblies in Oregon: Oregon Health Authority tester certification, the 5-day course, the 2-year cycle and the CCB license for paid work.
- Backflow testing in Colorado: Regulation 11 and certified techniciansColorado's backflow rule (Regulation 11, section 11.39): annual testing, ABPA or ASSE certified technicians, and why each water supplier runs its own program.
Sources (1)
- Washington Administrative Code 246-290-490, Cross-connection control · checked 2026-10-06