Lorton is unincorporated Fairfax County on Fairfax Water, so testable backflow assemblies on lawn irrigation, in-ground pools, directly connected hot tubs and fire sprinklers must be tested at installation, after repair or relocation, and at least yearly by a certified tester on the County's authorized list. To book a test or fix a device, call the number on this page to be connected with a local plumber in Lorton.

Lorton in brief
Lorton runs along I-95 and Route 1 between Fort Belvoir and the Occoquan River, and most of its housing is newer, with the 2000s the biggest building decade, including the Laurel Hill area. Many of those homes came with sprinkler systems, so backflow assemblies are common here and the originals are reaching the age when parts wear. Fairfax Water's Griffith plant, which treats Occoquan Reservoir water, sits near Lorton, and the utility runs its cross-connection program jointly with Fairfax County Land Development Services. Permits come from the County through PLUS, with Land Development Services at 703-222-0801.
What to do now
- Close the irrigation supply if water is escaping from the device.
- Check the date on any test tag or past report.
- Identify the type: a vacuum breaker has a cap on top, a reduced pressure unit has a relief opening underneath.
- Note what else is connected, such as a pool fill or a hot tub.
- Call a certified tester who holds the DPOR backflow credential and is on Fairfax County's authorized vendor list.
- Get the report submitted online by the tester and keep your own copy.
Common symptoms
| What you notice | Probable cause |
|---|---|
| Water from the relief opening while zones run | First check held open by grit or worn rubber |
| Spray from under the cap at start-up | Float or poppet seal worn |
| Brass split or a test cock broken off | Water froze inside |
| Low pressure across all zones | Partly closed shutoff or debris in the strainer |
| Green crust at fittings | Slow leak and corrosion |
Cost factors
- The test outcome. A pass is a single short visit; a fail adds parts and a retest.
- The assembly. Reduced pressure units and larger commercial devices take more time.
- Replacement. A new irrigation assembly needs a County plumbing permit.
- Reporting. Ask whether online submission is included in the price.
Fairfax Water's cross-connection line, 571-722-7653, can answer questions about a device on file at your address. Lorton winters bring freezing nights, so drain outdoor assemblies each fall; a split body found at the spring start-up turns a quick test into a replacement.
Backflow Testing questions in Lorton
Why does a lawn sprinkler system need a backflow preventer?
What does a backflow test actually involve?
What is the difference between a PVB, a double check and an RPZ?
Who pays for the test and any repairs?
More plumbing services in Lorton
Backflow Testing nearby
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