SeaTac · King County
Commercial backflow testing in SeaTac — hotels, parking & logistics
SeaTac’s economy runs on the airport: hotels, park-and-fly lots, rental car facilities, logistics and food service. All of it runs on water, and much of it carries high-hazard backflow assemblies that need annual tests filed with Highline Water District.
Highline Water program
How SeaTac’s backflow program works
The short version, summarized from the utility’s own cross-connection control materials.
Source: Highline Water District · verified October 2026 ↗Highline Water District serves SeaTac along with Burien, Des Moines, Normandy Park and parts of Kent, Tukwila and Federal Way.
Annual testing by a Washington State-certified tester is required.
Highline accepts test reports by email.
Report submission
We email your report to Highline’s backflow program the day we test, with a copy to you.
Questions for the utility: backflow@highlinewater.org · (206) 824-0375
On the ground
What we see in SeaTac
Every city’s housing stock and commercial mix shapes what’s in the meter box.
Hotels
Hotels carry domestic RPs, fire-line DCDAs, pool and spa protection, laundry and kitchen equipment assemblies — often 6–15 per property. We test them all in one coordinated visit.
Car washes & vehicle services
Car washes are on the state’s high-hazard list and need RP premises isolation. Rental and fleet facilities often have wash bays too.
Neighborhoods
Serving all of SeaTac
- International Blvd
- Angle Lake
- McMicken Heights
- Bow Lake
- Riverton Heights
- Military Road
FAQ
SeaTac backflow questions
01 Who can test my backflow assembly in SeaTac?
02 How do backflow test reports get submitted to Highline Water?
03 How much does backflow testing cost in SeaTac?
04 What if my assembly fails in SeaTac?
Field test report · next due
SeaTac test due? We’ll handle it.
Book online in two minutes. We test, repair if needed, and file the report with your water utility — and remind you next year.