Water heater flush in Dunn Loring.
A water heater flush in Dunn Loring is $99 right now, normally $199. Its 22027 homes get Potomac water treated at the Washington Aqueduct.
- Tank or tankless, any brand
- Priced before we start
- Pay after the visit
Book a flush or a descale
Dunn Loring’s water is hardest in December, the month the tank works hardest.
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.
Dunn Loring houses, by the numbers
From the Census Bureau’s 2020 to 2024 survey. Median year built and heat count owner-occupied homes only.
Dunn Loring
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.
- Median home built1991 Census
- Built before 1980about 3 in 10 Census
- Built since 2000about 2 in 10 Census
- Most homes aresingle-family houses, about 9 in 10 Census
- Heated withgas, about 7 in 10 Census
- Rentedhardly any Census
- In Dunn Loring, about 7 in 10 owner homes heat with gas. If the water heater is gas too, the flush includes a look at the burner and the vent.
What a water heater flush costs in Dunn Loring.
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.
Why people in Dunn Loring book a flush.
Lukewarm showers on the coldest mornings
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.
It pops or rumbles
That’s water boiling under a layer of sediment on the bottom of the tank. A flush clears it out.
Nobody knows when it was last done
Which is most houses. The drain valve at the bottom of the tank has usually never been opened.
How to pick who flushes your water heater in Dunn Loring.
Questions worth asking anybody you call, us included.
Do they know which water feeds your street?
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.
Do they check the anode rod and test the relief valve?
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.
On a tankless, do they pump descaler through it?
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.
What our customers say.
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
5.0 stars across 884 Google reviews. Read them on our reviews page.
Water heater flush questions from Dunn Loring.
How hard is the water in Dunn Loring?
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.
When’s the best time of year to flush in Dunn Loring?
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.
How much does a water heater flush cost in Dunn Loring?
$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.
Water heater flushes in the towns next door.
- Water heater flush in Vienna
- Water heater flush in Falls Church
- Water heater flush in McLean
- Water heater flush in Annandale
- Water heater flush in Oakton
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Book the flush, tank or tankless.
Call, or book online and pick a window. Tell us tank or tankless, and the tech brings the right gear.
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 884 Google reviews. SwiftPro maintains a dedicated HVAC team and a dedicated plumbing team.
SwiftPro Heating, Cooling & Plumbing, 4230 Lafayette Center Dr, Suite N, Chantilly, VA 20151, (703) 997-9757. Book online, read our reviews, or see every town we serve.