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Backflow testing in Annandale: Fairfax County sets your test month from your tax map grid, and across almost all of 22003 that’s January, February or March.
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What it costs
How many devices you have and what kind they are decide the number, so there isn’t one figure that fits every house. You get one flat price per device when you book, before anyone comes out.
Yearly backflow test
One flat price per device, given when you book
Repair or rebuild after a failed test
Priced in writing before any work
New backflow preventer, installed
Priced in writing before any work
A device that fails is priced in writing before any work. Most can be rebuilt with new springs, seats or rubber parts; a body cracked by a freeze gets replaced. Either way it’s tested again afterward, which Virginia requires.
The national numbers, and what moves a price up or down, are in our backflow testing cost guide.
What’s different in Annandale
In Fairfax County your lot picks the test date. Every property with a backflow preventer is tied to one month through the tax map grid it falls in, and the test belongs in that month, year after year. Nearly all of 22003 sits in grids the County’s chart puts in January, February or March: Broyhill Crest is grid 60, due in January; the blocks where Little River Turnpike meets Columbia Pike are grid 71, February; Wakefield Chapel Road and Wakefield Park are grid 70, March.
So the gauge goes on a sprinkler system that was blown out in the fall. A device you brought inside for the winter has to be back on before your month, and a report marked not in use or not tested gets turned away. On a pressure vacuum breaker, a winter test usually means opening the supply just long enough to put pressure on the device, keeping the valve past it shut so the drained lines stay dry, then draining it again. Book a day above freezing.
By the County’s own account, many, maybe most, lawn sprinkler systems were put in after people had moved in, with no permit, so nobody ever gave them a final inspection, and age doesn’t grandfather one. And it’s an old rule: Virginia has called for a tested, high-hazard assembly on in-ground sprinklers since the early 1970s. Annandale’s typical owner home went up in 1967, before that rule, and only about 5 homes in 100 have gone up since 2000. The device the County most often finds put in wrong is a dual check, which has nothing to test. Can’t tell what’s on yours? Ask the County’s program for a site visit; it doesn’t charge for one.
Wakefield, the Census place west of the Beltway around Canterbury Woods, is about 95 in 100 single-family houses and fewer than 1 in 10 rented, so a notice there usually means the owner’s own sprinklers or pool. In the Annandale Census place roughly one home in three is rented, and in Woodburn about 4 in 10. The County’s notice goes by mail or email to whoever it has on file, and telling it about a new owner or a landlord’s agent is on you. More in our Fairfax County backflow guide.
Neighborhood by neighborhood
Census figures for the owner-occupied homes in each place, and what usually brings the test notice to houses like these.
| Place | Median home built | Most homes are | Heated with | What usually needs the test |
|---|---|---|---|---|
| Annandale | 1967 | single-family houses, about 5 in 10 | gas, about 7 in 10 | A sprinkler system or pool added later, where there is one. |
| Wakefield | 1968 | single-family houses, nearly all | gas, about 8 in 10 | A sprinkler system or pool added later, where there is one. |
| Woodburn | 1968 | single-family houses, about 4 in 10 | gas, about 6 in 10 | A sprinkler system or pool added later, where there is one. |
By the numbers
From the Census Bureau’s 2020 to 2024 survey, owner-occupied homes unless it says otherwise.
When it’s time
Sprinklers a previous owner installed can sit unused for years. If the County has a testable device on record at your address, it still wants a passing test every year, and removing the device for good needs the County’s approval.
A letter from the water utility with a date on it means there’s a testable device on your line, usually on the lawn sprinklers, and its test is due.
On an RPZ, a little water when the pressure jumps can be normal. A steady stream from the opening underneath means a check valve isn’t sealing, and it won’t pass.
Before the first hard freeze
A device that sits full of water all winter is the most common reason it fails the spring test. Around here, get this done by the end of October.
On most houses it’s outside by the foundation: a brass valve on two pipes standing out of the ground, with a cap on top. That’s a PVB. An RPZ or double check may sit in a basement or a box in the ground instead.
Turn off the valve that feeds the sprinklers, usually in the basement or utility room just past the main shutoff. Leave the rest of the house on.
Most systems here get blown out with compressed air so nothing sits in the lines or the device. If yours hasn’t been, that’s the step that matters.
Set the device’s two shutoff handles and its little test cocks about halfway, near 45 degrees, so no pocket of water stays trapped inside to freeze.
An insulated cover helps a PVB through the winter. On an RPZ, never block the relief valve opening underneath: it has to be able to dump water.
Some owners bring the device inside for the winter. Check the rules first: Loudoun Water wants a device that came off tested again when it goes back on, and Fairfax County wants it back on before your testing month.
Not sure it was drained, or saw water coming from the cap when the sprinklers ran? Call us. We’ll look at it, and if it cracked, you get the reason and a price before anything gets replaced.
Who sends the notice
Fairfax County’s Cross Connection Program wants testable backflow devices on lawn sprinklers, fire sprinklers, pools and hot tubs tested every year by a tester on the County’s Authorized Vendor List. The tester files the report and the County emails you when it’s in; nothing after 14 days, and the County asks you to check with them. Source.
Each property gets its own testing month from the County’s tax map grid, and the report is due before that month ends. A device that fails has to be repaired or replaced and retested within 10 business days of the failed test, and one taken off for the winter goes back on before the testing month. Source.
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Choosing a tester
Questions to ask anybody who offers to test it, us included.
Ask whether they’ll test in winter, drain the device again before they leave, and get the report to the County before your month runs out.
Since January 1, 2023, Virginia only accepts tests from a DPOR-certified Backflow Prevention Device Worker, and some places keep a list of their own on top. Ask to see the certificate before the gauge goes on.
Some utilities take it from the tester and some want it from you. Ask which, and keep a copy either way, so you can show the date if a second notice turns up.
Ask for the reason and a written price before anything gets taken apart, and whether the retest is part of it. A failed device runs on a deadline, so a tester who can also fix it saves you a second trip.
Two of our crew going over a work order before the day's calls.
From our Google reviews
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My technician James gave an honest assessment of my situation, clearly laid out the scope of work, and provided different pricing options to resolve my concern. I will definitely call SwiftPro in the future for any plumbing needs!
Where we work
Next door to Annandale: Fairfax, Alexandria, Reston, Centreville and Woodbridge.
Questions
Whatever month the County’s chart gives your grid. Across nearly all of 22003 that’s January for grids 58, 59 and 60, February for 61, 69, 71 and 72, and March for 70. Your grid is the first three digits of the tax map number on your County real estate record.
Fairfax County gives you 10 business days from the failed test to repair or replace it and pass a retest. A body split by frost usually means a new device, and that takes a plumbing permit.
One flat price per device, given when you book, before anyone comes out. How many devices you have, and whether one needs a repair, is what moves it. Our cost guide has the national numbers.
About 30 minutes a device. The water is off for a few of those minutes while the gauge readings are taken.
Ready when you are
Call, or send the form at the top. Have the notice handy: how many devices it lists and the date on it are what we need.
SwiftPro Heating, Cooling & Plumbing
4230 Lafayette Center Dr N, Chantilly, VA 20151
44679 Endicott Dr, Suite 211, Ashburn, VA 20147
Virginia Class A contractor license #2705192276
SwiftPro Heating, Cooling & Plumbing is a licensed, BBB Accredited (A rating), independently owned heating, cooling and plumbing company in Chantilly, serving Annandale and the rest of Northern Virginia. Virginia contractor license #2705192276. 5.0 stars across 1,131 reviews on Google, Angi, Yelp, the BBB and Facebook. SwiftPro maintains a dedicated HVAC team and a dedicated plumbing team.
From SwiftPro Heating, Cooling & Plumbing in Chantilly. Housing figures are the Census Bureau’s American Community Survey, 2020 to 2024, for each place named; permit, water and sewer facts link to each office’s own page and were checked in September and October 2026.