5.4 Backflow Testing, Certified Testers, & Washington's Cross-Connection Program (WA 603.4.2; WAC 246-290-490, 246-292)

Key Takeaways

  • Washington's 603.4.2 requires backflow assemblies to be tested by a DOH-certified backflow assembly tester at installation, repair, or relocation and at least annually thereafter.

  • WAC 246-290-490 also requires inspection and testing after a backflow incident and annually unless the purveyor requires more frequent testing.

  • A BAT's field test kit must be pressure-tested and accuracy-checked by an independent laboratory within the 12 months before a test (WAC 246-292-034).

  • DOH operator certificates, including BAT certificates, are valid until December 31 each year and are renewed annually (WAC 246-292-090).

  • For an existing high health hazard, the purveyor must see backflow protection installed within 90 days of notifying the consumer, or on an alternate acceptable schedule (WAC 246-290-490).

Last updated: September 2026

Who Tests, and When

Washington amendment to UPC 603.4.2: For devices other than those the Department of Health regulates with the purveyor, the AHJ must ensure the premises owner or responsible person has each backflow prevention assembly tested by a Washington State Department of Health certified backflow assembly tester (BAT):

  1. At the time of installation, repair, or relocation, and
  2. At least annually thereafter, unless the AHJ requires more frequent testing.

Washington's amendment to 603.2 adds several related duties:

  • The person in control must maintain every device in good working order.
  • A defective device must be repaired or replaced.
  • No device may be removed, relocated, or substituted without AHJ approval.
  • Testing must be done by a DOH-certified BAT.

Washington's definition 205.0 says a certified backflow assembly tester is certified by DOH under chapter 246-292 WAC. A BAT inspects and tests assemblies, and maintains and repairs them in compliance with chapter 18.106 RCW.

The Purveyor's Program (WAC 246-290-490)

Every public water system purveyor must run a written cross-connection control program. Its required elements include:

ElementRequirement
Legal authorityA local ordinance, resolution, code, or bylaw establishing the program and corrective actions
Hazard evaluationEvaluate new connections before service starts (connections made on or after April 9, 1999); re-evaluate periodically and whenever the use changes
StaffingAt least one Cross-Connection Control Specialist (CCS)
Testing quality controlDocumentation of BAT certification and test kit calibration, test report contents, and time frames for submitting reports, all set by the purveyor
RecordsKeep incident records and annual summary reports for 5 years; file an annual program summary report
Corrective actionMay deny or discontinue water service until the hazard is controlled, or require or install a premises isolation assembly. The AHJ must be notified first, except in an emergency

Inspection and testing duties (WAC 246-290-490(7))

  • A CCS inspects backflow preventer installations for protection commensurate with the hazard.
  • A BAT or CCS inspects air gaps and assemblies for correct installation and approval status.
  • Only a BAT tests assemblies for proper operation.
  • When: upon installation, repair, reinstallation, or relocation; upon installation or replumbing of an air gap; after a backflow incident; and annually thereafter. The purveyor may require more frequent tests for high-hazard premises or assemblies that repeatedly fail.
  • AVBs on irrigation systems are inspected at installation, after an incident, and after repair, reinstallation, or relocation.
  • Tests use procedures acceptable to DOH, such as the USC Manual of Cross-Connection Control.

Retrofit timelines

  • New connections (on or after April 9, 1999): protection is installed and tested before service is provided.
  • Existing connection with a high health hazard: installed within 90 days of the purveyor's notice, or on an alternate schedule acceptable to the purveyor.
  • Existing low hazard: on a schedule acceptable to the purveyor.

BAT Certification and Test Kits (WAC 246-292)

  • Certification: Apply to DOH, then pass a computer-based examination and a DOH practical examination.
  • Renewal: Certificates are valid until December 31 each year and are renewed annually. BATs must also pass a professional growth examination during each professional growth reporting period.
  • Test kit: The kit must be evaluated, pressure-tested, and checked for accuracy by an independent laboratory at least once within the 12 months before a test. It must be recalibrated, repaired, or replaced if it fails.
  • Reports: The BAT gives a completed inspection and field test report to both the owner and the purveyor. The report includes the kit's information, the BAT's certification number, the readings, and the BAT's signature.

Field Test Criteria (ASSE Series 5000 and USC Methods)

UPC 603.4.2 requires testing by procedures in the ASSE Series 5000 standards. Common passing criteria:

AssemblyComponentPassing result
RPDifferential relief valveOpens at 2.0 psid or more
RPFirst checkHolds at least 5.0 psid, and more than the relief valve opening point
RPSecond checkHolds tight against backpressure
DCFirst and second checksEach holds at least 1.0 psid
PVB / SVBAir inletOpens at 1.0 psid or more and fully opens
PVB / SVBCheck valveHolds at least 1.0 psid

An RP that discharges steadily from its relief port under normal flow usually has a fouled first check. That lowers the zone differential until the relief valve opens. Testers isolate and test the first check before blaming the relief valve.

Where the Plumber Fits

CredentialIssued byScope
Journey level plumber (PL01)L&IInstalls, replaces, and repairs backflow assemblies as plumbing work
Backflow specialty plumber (PL30)L&IMaintenance and repair of assemblies inside buildings. Requires a current DOH BAT certification to apply. Does not include installing or replacing assemblies
BATDOHInspects and field tests assemblies and air gaps protecting the public system; signs test reports
CCSDOHRuns the purveyor's program and assesses hazards

A journey level plumber who is not also a BAT cannot sign a test report. A BAT who is not certified by L&I cannot perform plumbing work that requires a plumbing certificate.

Test Your Knowledge

A reduced pressure principle assembly was just installed on a boiler makeup line in Washington. Under Washington's amendment to UPC 603.4.2, when must it be tested?

A

Only after the first year of operation

B

At installation, repair, or relocation, and at least annually thereafter, by a DOH-certified backflow assembly tester

C

Every three years with the building permit renewal

D

Only if the purveyor detects a pressure drop

Test Your Knowledge

How recently must a BAT's field test kit have been checked for accuracy by an independent laboratory under WAC 246-292?

A

Within 30 days of each test

B

Within the 12 months before the inspection and field test date

C

Within the last 3 years

D

Only when the kit is new

Test Your Knowledge

A purveyor notifies an existing mortuary that its service connection is a high health cross-connection hazard. Under WAC 246-290-490, how quickly must premises isolation be installed unless an alternate schedule is accepted?

A

Within 90 days of the purveyor's notice

B

At the next annual test

C

Within 24 hours

D

Within 30 days

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