Start with the homes. Canal-front homes along Highway 106 from 1940s cabins to substantial 1990s and 2000s rebuilds, hillside homes in Union Ridge and Vuecrest from the 1970s onward, and a mix of manufactured and custom homes on the uplands. A high share of second homes and retirees. It is about 50 minutes from Port Orchard, west on Highway 3 to Belfair and then Highway 106 along the South Shore of Hood Canal to Union, a run we make often enough to know the roads, the water districts and the quirks of the housing.
Why backflow preventer installation is a little different in Union
Newer homes in Union with residential fire sprinklers frequently have a double check assembly in the garage or crawlspace that nobody has looked at since the house was built. We inspect, test-coordinate and replace those when they fail.
The ground is the other half of the story. The south shore of the Great Bend, with a narrow shoreline bench, Highway 106 running along it, and steep bluffs and benches rising behind. Thin soil over glacial deposits on the slopes, and a water table at the surface along the shoreline in winter.
Local conditions that affect backflow preventer installation in Union
The pattern we see most in Union is this: Well pressure tanks and switches on upland properties
HOAs and property managers around Union often have a dozen assemblies across several buildings. We keep an inventory of makes, models and locations so annual testing and replacements go quickly and nothing gets missed.
Local conditions shape the work. In Union: Scale on tankless and tank heaters from mineral-rich groundwater
Rural parts of Union on community water systems often still have an old well on the property. The purveyor treats that as a cross-connection, and we resolve it with either an RPZ on the service or a documented disconnection of the well piping.

Signs Union homeowners call us for backflow preventer installation
Worth a call
- You are adding an irrigation system, fire sprinklers, a boiler or a pool auto-fill
- Your property has both a private well and a city water connection
- An old assembly is corroded, the shutoffs will not close, or the test cocks are seized
- A home inspector or county inspector flagged a cross-connection
- The brass body cracked in a winter freeze
How we handle backflow preventer installation in Union
When a Union homeowner books backflow preventer installation, the job unfolds as figure out what the purveyor wants, site check and flat quote, install with testable access, initial certification, then record and remind, and you can watch and ask questions the whole way.
Read the full step-by-step for backflow preventer installation →
Union neighborhoods and areas we serve
Call from Highway 106 canal frontage, Skokomish Valley edge or anywhere else in Union, including the places near Union Country Store and Twanoh State Park that other outfits treat as a long drive.
Backflow Preventer Installation questions from Union
My backflow test failed in Union. Do I have to replace the device?
Not always. If the body is sound we rebuild it with new checks and springs, which is far less than replacement. If the body is pitted or the shutoffs are gone, we recommend a new assembly and show you why.
Can you winterize a backflow assembly in Union?
Yes. We add drain ports and blowout access during installation and can retrofit them to existing devices, and we offer insulated enclosures for assemblies exposed to the Mason County east wind.
Do you handle the paperwork for the Union water district?
We coordinate the initial certification test and make sure the report reaches your purveyor. You get photos and device details for your own records.
Is a permit needed to install a backflow preventer in Union?
Usually a plumbing permit is required, and the purveyor needs the installation and test report. We take care of both as part of the job.
What is the difference between a double check and an RPZ?
Both have two check valves in series. The RPZ adds a relief valve between them that opens and dumps water if either check leaks, which is why it protects against higher hazards and why it has to be above ground with room to discharge. The double check can go in a below-grade vault.
Mason County is well-water, septic and long-driveway country, and we are set up for it. Washington Plumbing & Drain reaches Union from Port Orchard by way of Belfair, with trucks stocked for pump houses and remote lots.

