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Backflow testing in Gainesville, 20155: the yearly Prince William Water test, a rebuild if the device fails, and a report you can check before it goes in.
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Licensed and insuredVirginia Class A contractor #2705192276
24/7 emergency serviceOften same-day, and we will tell you honestly when we can get there.
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The price is settled before the workYou see the number in writing before anything is taken apart
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 Gainesville
In the part of 20155 the Census counts as Gainesville, about eight owner homes in ten went up in 2000 or later, roughly half of those in the 2000s. Where a builder put the sprinklers in, the PVB by the foundation is usually still the original, and on a 2000s home it has stood outside for about twenty winters. Rubber seats and springs wear with age, so a device that always passed can fail one spring with no leak to warn you.
Plenty of lots got sod and no sprinklers, and about a third of homes here are townhouses. Adding a system? In Prince William the backflow device on a home’s sprinklers takes a Limited Service and Repair Permit and an inspection, and has to be an atmospheric vacuum breaker, a PVB or an RPZ. Keep the heads out of the public right-of-way, which on a street with a sidewalk generally ends a foot behind it: county guidance says sprinklers there come out at the owner’s expense before the state takes over a new street.
Some of what comes out of a Gainesville tap starts in Lake Manassas, which Prince William Water blends with Potomac water for this side of the county. Virginia Oaks backs onto that shoreline, and its association’s guidelines go as far as recommending a hose-end weed sprayer with a backflow preventer built into the bottle. The device on your sprinkler line does the same job for the whole yard.
Here the job isn’t done when the gauge comes off. Prince William Water holds the owner responsible for the approved results reaching its Cross Connection Coordinator, so make sure the report went in and keep your copy for the house file. Questions about a notice go to crossconnections@pwwater.org. The county’s rules, antifreeze included, are on our Prince William County backflow page.
By the numbers
From the Census Bureau’s 2020 to 2024 survey, owner-occupied homes unless it says otherwise.
When it’s time
Close to one Gainesville owner home in ten is from 2020 or later. Virginia has a device tested when it goes in and every year after, and Prince William Water mails the reminder to the owner, not the builder, so the first letter can land within about a year of moving in.
In a newer subdivision the builder often put in the lawn sprinklers, and the backflow device with them. Nobody tells the next owner it needs a test every year until the first notice shows up.
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.
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
Prince William Water mails a notice when a device comes due each year. Its test report form is made for the tester to send in, but the owner gets a copy of the approved results and is responsible for getting the forms to the utility’s Cross Connection Coordinator. Source.
County code says every lawn sprinkler system needs a backflow device, and a system winterized with antifreeze can only use an RPZ. Source.
Our Virginia Class A contractor license, 2705192276, is on the side of the van.
Choosing a tester
Questions to ask anybody who offers to test it, us included.
Depending on the builder, it can be a PVB by the foundation, an RPZ indoors, or vacuum breakers on each zone. Ask the tester to name yours on the report. That settles the fall question: Prince William allows antifreeze in the lines only behind an RPZ.
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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Tyson was wonderful; professional, very knowledgeable, thorough and fast. He was great at telling me about what was needed, and I very much appreciated that. For the next plumbing problem we have, I will have SwiftPro on speed dial.
Where we work
Next door to Gainesville: Bristow, Centreville, Chantilly, Manassas and Aldie.
Questions
Prince William Water mails notices for the testable devices on its records. No sprinklers, or atmospheric vacuum breakers on the zones, means nothing to test: those have no test cocks. If there’s a PVB by your foundation and no letter has ever come, ask the utility’s cross connection office.
Usually not. A device on a condominium building’s line or on the common grounds is normally the association’s to test. Heritage Hunt, the 55 and over community by the I-66 Gainesville exit, has detached houses too, and one with its own sprinklers gets its own notice. Ask management before you book.
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 Gainesville 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.