The rule in one paragraph
Every public water system in Washington must run a cross-connection control program under WAC 246-290-490. A cross-connection is any point where drinking water could connect to something that isn’t drinking water — an irrigation system, a boiler, a fire sprinkler line, a chemical dispenser. Where one exists, the utility requires a backflow preventer suited to the hazard, and requires approved backflow assemblies to be tested by a state-certified tester. The utility — Seattle Public Utilities, Tacoma Water, your city or water district — is who enforces it, which is why the notice comes from them.
The only way to know a backflow assembly works is to test it. Springs weaken, rubber hardens, and grit lodges in seats — all invisibly.
When an assembly must be tested
Under WAC 246-290-490, approved backflow assemblies are tested:
- On installation, and after any repair, reinstallation or relocation;
- Annually after that — or more often if your utility requires it;
Many utilities add their own triggers on top — Lynnwood, for example, also requires a test after a backflow incident.
Atmospheric vacuum breakers (AVBs) on irrigation can’t be field-tested, so instead they’re inspected at installation, after a backflow incident, and after repair, reinstallation or relocation.
Your utility sets the actual due date. Tacoma Water, for example, assigns each assembly a due date and expects the test by then regardless of when the previous test was done.
Who can test
Only a Backflow Assembly Tester (BAT) certified by the Washington State Department of Health. The certification program is administered by Washington Certification Services at Green River College. Candidates must pass a one-hour hands-on practical exam — testing a PVBA, SVBA, DCVA and RPBA, with simulated malfunctions to diagnose — and a 100-question computer-based exam. Certified testers must also pass a professional-growth exam each reporting cycle to stay certified.
Testers must use a differential-pressure test kit with a current accuracy verification, and most utilities require the tester’s BAT card and test-kit calibration on file before they’ll accept a report. Anyone can check a tester’s status on the public BAT lookup.
Who can repair & install
This is where people get tripped up. A BAT certificate alone covers testing. Washington DOH’s guidance (publication 331-680) lays out what’s required for each kind of work:
| Work | DOH BAT | Contractor registration | L&I plumber certificate |
|---|---|---|---|
| Testing & inspection (any assembly) | Required | No | No |
| Install, repair, maintain — outside buildings | Advised | Required (RCW 18.27 or 18.106) | No |
| Repair & maintain — inside residential buildings | Advised | Plumbing contractor | PL01, PL02 or PL30 |
| Repair & maintain — inside commercial buildings | Advised | Plumbing contractor | PL01 or PL30 |
| Install — inside residential buildings | Advised | Plumbing contractor | PL01 or PL02 |
| Install — inside commercial buildings | Advised | Plumbing contractor | PL01 |
PL01 = journey-level plumber · PL02 = residential plumber · PL30 = backflow specialty plumber (maintenance and repair of existing assemblies inside buildings; requires an active BAT certification). Source: WA DOH 331-680.
Fire sprinkler lines: the Washington State Patrol requires State Fire Marshal certification for people who inspect and test water-based fire sprinkler systems, but it exempts state-certified BATs while they’re inspecting, testing and maintaining backflow assemblies.
Which assembly you need
The protection required depends on the degree of hazard. Your utility’s cross-connection control specialist makes the final call. Generally:
- High health hazard — hospitals, clinics, labs, mortuaries, car washes, food and beverage processing, metal plating, chemical plants, docks and piers, irrigation with chemical injection, and more. These typically require a Reduced Pressure Backflow Assembly (RPBA) at the meter as premises isolation. Seattle Public Utilities publishes its own list.
- Low hazard — most irrigation systems, standard fire sprinkler systems, and buildings over 3 stories or 30 feet (in SPU’s program). These can typically use a DCVA, or for back-siphonage-only situations like irrigation, a PVBA or SVBA.
Every assembly must be a model on the current list approved for use in Washington — the University of Southern California Foundation for Cross-Connection Control and Hydraulic Research list. See our assembly types guide for what each one does.
What goes on a test report
WAC 246-292-036 spells out what a BAT’s field test report must include: the facility and assembly location; make, model, size and serial number; whether the installation is correct; the test kit used and its most recent accuracy verification; the actual readings from the initial test; any repairs and the retest readings; and the tester’s signature and certification number. The tester must have personally inspected and tested the assembly.
An incomplete report is a rejected report. Lynnwood, for one, says so explicitly.
If you don’t test
WAC 246-290-490 lets a utility take corrective action when a consumer doesn’t comply — up to denying or discontinuing water service until the hazard is controlled. In practice, utilities escalate: reminder, second notice, non-compliance charges, then shutoff. Examples:
- Seattle Public Utilities may assess non-compliance charges and possibly terminate water service.
- Tacoma Water may assess a $100-per-occurrence penalty, require an assembly at the meter at the owner’s expense, and/or terminate service.
- Kirkland requires a failed assembly to be repaired and retested within five business days.
Checklist for owners
- Find your due date on the utility notice (or call the utility).
- Hire a Washington-certified BAT — verify them.
- Make sure the assembly is accessible and the water supply to it is on.
- If it fails, get it repaired by someone properly licensed for the location (outside vs. inside the building) and retested.
- Confirm the tester filed the report with your utility, and keep your copy.
- Put next year’s date on the calendar — or let us remind you.
This guide summarizes public regulations and utility materials for general information; it isn’t legal advice. Your utility’s requirements and notice always govern.
