Backflow Testing in Seattle: Rules, Costs, Testers

Backflow testing in Seattle

In the Seattle area, each water utility runs its own backflow program: Seattle Public Utilities and Tacoma Water each set who must test, when the report is due and how it is filed. 54 listed testing companies work within 30 miles of Seattle.

Each fact links the page it came from. Utility and state pages were read October 6 and 7, 2026.

Who has to test in Seattle

The rule depends on the utility that sends your water bill. Each line below is from that utility's own page.

Seattle Public Utilities: All installed backflow assemblies must be tested every year by a State of Washington certified backflow assembly tester, and after any repair or replacement; a copy of the report goes directly to SPU.
Tacoma Water: Tacoma Water requires a Washington-certified backflow assembly tester (BAT) to inspect assemblies after installation and test them every year, and requires a copy of each test report.

Sources: Seattle Public Utilities; Tacoma Water

How each utility takes the test report

Most utilities here take the report online through a vendor portal; the tester files it. Open a utility for its own deadline, filing steps and fees.

Utility	Report filed through	Approved tester list	Published fee
Seattle Public Utilities	SAMS (NJBSoft)	Posted list	None found
Tacoma Water	See the utility page	Posted list	None found

What testing costs in Seattle

These are amounts the utility or a company published on its own page, shown as published, never averaged.

Backflows Northwest, Bellevue: Backflows Northwest residential test starting price, $73.00 (date not shown).

Source: Backflows Northwest, Bellevue

If the test is missed

Seattle Public Utilities: If testing is not completed, SPU may assess non-compliance charges and may terminate water service.
Tacoma Water: If an assembly is not tested, Tacoma Water may add a $100 fee per assembly to the bill and keep adding fees until testing is done, install an RP at the meter at the owner's expense, or terminate water service.

Sources: Seattle Public Utilities; Tacoma Water

Washington rules behind the local programs

State rules set the minimum; the utilities above add their own deadlines and tester registration.

Under WAC 246-290-490(7)(b)(ii), assemblies are tested at installation, after repair or relocation, after a backflow incident and every year after; the purveyor may require more often for high hazard premises or repeated failures.
A certified Backflow Assembly Tester (BAT) does the tests (WAC 246-290-490(7)(a)(iii)).
Atmospheric vacuum breakers on irrigation systems are inspected at installation, after a backflow incident and after repair or relocation, rather than tested every year (WAC 246-290-490(7)(c)).

Sources: Washington rule; Washington rule; Washington rule

Common questions

Who requires backflow testing in Seattle?

Your water utility. Seattle Public Utilities and Tacoma Water each run a program; check the notice your utility sends for your due date.

How is the test report filed?

Online in most cases: at least one utility here uses SAMS (NJBSoft). The tester files the report; ask them to send you a copy.

Backflow testing companies near Seattle

What the badges mean

✓ WA Utility-Approved Tester Verified On the city list: The company is on a water utility's own approved list (the second badge names the list). That is the utility's approval, not a state license, and it counts for that utility.
3 certified testers: How many certified testers the roster lists at this business.
★ 4.8 (25 reviews): The Google rating, shown as Google reports it. It does not change the order.

Order is by our quality score, never by payment. How we verify listings.

McKinstry

90/100

✓ WA Utility-Approved Tester Verified ★ 3.8 (67 reviews) On City of Bellevue list Backflow Testing

5005 3rd Ave S, Seattle, WA 98134 · under 1 mile from Seattle

Call (206) 762-3311 Details Website