Open 24/7 for emergencies
A water heater flush in Dunn Loring is $99 right now, normally $199. Its 22027 homes get Potomac water treated at the Washington Aqueduct.
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Rather talk now? (703) 997-9757
5.0 stars across 1,132 reviews
Two of our technicians in a customer’s basement, next to the furnace and a tank water heater.
Licensed and insuredVirginia Class A contractor #2705192276
24/7 emergency serviceOften same-day, and we will tell you honestly when we can get there.
Our own plumbers, our own trucksNobody here is a subcontractor with a magnet on the door
The price is settled before the workYou see the number in writing before anything is taken apart
What it costs
Same prices as our water heater flush page, anywhere in Northern Virginia, and you pay after the visit.
Tank water heater flush, with the plumbing check
$99, normally $199
Tankless descale, with the plumbing check
$300, regularly $350
Comfort+ membership, a water heater flush with a sewer camera inspection every year included
$199 a year
Both visits include a whole-home plumbing check: supply lines, shutoffs, a pressure reading, drains, toilets and traps.
One per household, owner-occupied homes, limited time. A leaking tank, or one that’s 15 years old, needs repair or replacement, not a flush.
More for the money: Comfort+ membership, $199 a year, includes the flush and its plumbing check every year, plus a sewer camera inspection, a dryer vent cleaning and heating and cooling maintenance visits.
What’s different in Dunn Loring
Every house with a 22027 address sits inside the part of Fairfax Water’s map served from the Washington Aqueduct. That’s Potomac River water, treated by the Army Corps of Engineers at its Dalecarlia and McMillan plants. The Aqueduct’s 2025 report puts its hardness between 96 and 187 milligrams per liter, about 5.6 to 10.9 grains per gallon, plenty of calcium to lay a fresh layer of grit on the bottom of a tank each year.
The figure moves with the river. It runs lowest in May and June and highest in December, which is the wrong month for a water heater: the water coming in from the street is near its coldest, so the burner runs longest on the hardest water of the year. NOAA’s normals for its Vienna station, 3.6 miles west, put the average January low near 23 degrees. A flush in the fall clears last year’s sediment before that stretch begins.
One corner drinks something else. Carnegie, Bucknell, Wesleyan and the other college-named streets off Cottage Street, with Vienna mail, buy Town of Vienna water, and the Town’s 2025 report calls it moderately hard to hard, 5 to 10 grains per gallon. Close enough that the advice doesn’t change: a yearly flush for a tank, and a yearly descale for a tankless that has no softener ahead of it.
The plumbing check that comes with every flush includes a pressure reading. Fairfax Water promises 20 psi at the main and nothing uniform past it, and the pressure reducing valve on the house side of the meter is the owner’s to keep up. In a house built around 1991 that valve may be the original. When one starts letting pressure creep up, it shows on the gauge before it shows as a dripping relief valve on the tank.
By the numbers
From the Census Bureau’s 2020 to 2024 survey. Median year built and heat count owner-occupied homes only.
ZIP 22027 as a whole: every Dunn Loring address. The Dunn Loring Census place is bigger: about three in four of its homes have Vienna mail.
When it’s due
In deep cold the water feeding the tank is at its coldest, and sediment on the bottom leaves less room and slows the heating. During the late January 2026 cold, NOAA’s records note wind chills of 0 to 10 below across the Piedmont. If the hot water ran short that week, start with a flush.
That’s water boiling under a layer of sediment on the bottom of the tank. A flush clears it out.
Which is most houses. The drain valve at the bottom of the tank has usually never been opened.
Choosing who does it
Questions worth asking anybody you call, us included.
Most of Dunn Loring is Fairfax Water’s Aqueduct water, but the college-named streets are Town of Vienna water, each with its own report. A plumber who knows which you’re on can tell you what your tank has been living with.
The anode is the part that corrodes so the tank doesn’t, and the relief valve is the tank’s safety valve. A flush that skips both is just draining water.
A real descale isolates the heater at its service valves and pumps solution through the heat exchanger, then rinses it and cleans the inlet screen.
Two of our crew going over a work order before the day's calls.
From our Google reviews
5.0 stars across 1,132 reviews. Read them on our reviews page.
James plumbing Tech was Friendly and Professional. Very well communicated. My water heater tank is top-notch and looks awesome. Highly recommend James nickname (Jimbo)and customer service. Thank you guys
Where we work
Next door to Dunn Loring: Vienna, Falls Church, McLean, Annandale and Oakton.
Questions
Moderately hard to hard most of the year. The Aqueduct water most of Dunn Loring gets ran 5.6 to 10.9 grains per gallon in 2025, and the Town of Vienna water in the southwest corner 5 to 10. Either is enough for a yearly flush, $99 right now.
Early fall, before the heat runs every night. The Aqueduct’s water climbs toward its hardest in December while the street water gets colder, so a tank that starts November clean has the easiest winter.
$99 right now for a tank, normally $199, with a whole-home plumbing check. A tankless descale is $300 right now, regularly $350. Comfort+ membership, $199 a year, includes the flush every year.
Ready when you are
Call, or send the form at the top. Tell us tank or tankless, and the tech brings the right gear.
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 Dunn Loring and the rest of Northern Virginia. Virginia contractor license #2705192276. 5.0 stars across 1,132 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.