The hot side stayed discolored after the cold cleared
After the spring hydrant flushing the cold tap clears quickly. Hot water that stays rusty or gritty after that is a tank holding sediment.
Annandale, Virginia
Water heater flush in Annandale.
Water heater flushes and tankless descaling in Annandale, 22003, on Fairfax Water’s hard water. $99 for a tank flush right now.
Get your price in writing
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Rather talk now? (703) 997-9757
- Tank or tankless, any brand
- Priced before we start
- Pay after the visit
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
What a water heater flush costs in Annandale.
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 Annandale
In Annandale the tank is usually downstairs by a floor drain, the easy kind to flush.
Annandale’s houses are old enough that the water heater in yours isn’t the first. The median owner home went up in 1967, so the tank there now is probably the house’s third or fourth, and its label tells us its age before anything else. In a rambler or split-level of that era it usually stands on the lowest floor beside the furnace, a few steps from a floor drain, which keeps the flush simple.
The water comes from Fairfax Water, supplier to 97 percent of Fairfax County’s residents. Its two plants measured 3 to 10.8 grains per gallon in 2025. Fairfax Water says northern homes generally get the Potomac plant’s water and southern homes the Occoquan plant’s; Annandale sits in the middle, so we plan around the high number. The Potomac plant read 70 milligrams per liter in May and 185 by November, so a tank takes in its hardest water in the fall.
Each spring Fairfax Water opens hydrants to flush its mains, late March through June this year, and it warns that the flushing can bring brief discoloration and sediment into the house. Whatever reaches the water heater settles on the bottom of the tank, where the water sits stillest. If grit keeps turning up at your taps, Fairfax Water’s rules let it reimburse part of a sediment filter, once per house.
Condos are the exception. About one Annandale home in five is in an apartment or condo building, and there the heater usually lives in a closet with a pan under it and no floor drain, so we drain it into buckets or the washing machine’s drain line instead.
Neighborhood by neighborhood
Where the water heaters are across Annandale.
Census figures for each place, and what we’d look at first on a flush there. Median year built and heat count owner-occupied homes only.
| Place | Median home built | Most homes are | Heated with | What we’d look at first |
|---|---|---|---|---|
| Annandale | 1967 | single-family houses, about 5 in 10 | gas, about 7 in 10 | Older houses on their second or third heater: we read the label first. |
| Wakefield | 1968 | single-family houses, nearly all | gas, about 8 in 10 | Older houses on their second or third heater: we read the label first. |
| Woodburn | 1968 | single-family houses, about 4 in 10 | gas, about 6 in 10 | Older houses on their second or third heater: we read the label first. |
By the numbers
Annandale houses, by the numbers
From the Census Bureau’s 2020 to 2024 survey. Median year built and heat count owner-occupied homes only.
Annandale
- Built before 1980about 8 in 10 Census
- Built since 2000about 1 in 10 Census
- Most homes aresingle-family houses, about 5 in 10 Census
- Heated withgas, about 7 in 10 Census
- Rentedabout 3 in 10 Census
- In Annandale, 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.
- In Annandale, about 8 in 10 homes were built before 1980, so the water heater has been replaced at least once. The label says how old this one is, and we’ll tell you what that means.
When it’s due
Why people in Annandale book 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.
Choosing who does it
How to pick who flushes your water heater in Annandale.
Questions worth asking anybody you call, us included.
Do they take a pressure reading while they’re there?
In a house built before December 4, 1972, the date Fairfax County’s plumbing code began calling for pressure reducing valves, there may be no valve on the line at all. A gauge on a spigot takes a minute, and high pressure is hard on a tank’s relief valve. Ours is part of the plumbing check.
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.
Two of our crew going over a work order before the day's calls.
From our Google reviews
What our customers say.
5.0 stars across 1,132 reviews. Read them on our reviews page.
This Company installed a tankless water system!!! They were great!!! Very Professional & Efficient & they Cleaned up & took out the old water tank! I would highly recommend them!!
Where we work
Water heater flush in every Northern Virginia town we serve
Next door to Annandale: Falls Church, Springfield, Dunn Loring, Burke and Fairfax.
Fairfax County
Arlington County
Loudoun County
Prince William County
Fauquier County
Stafford County
Questions
Water heater flush questions from Annandale.
Is the water hard in Annandale?
Yes, by most measures. Fairfax Water’s two plants ran 3 to 10.8 grains per gallon in 2025, hardest in the fall. Enough to build sediment in a tank every year, so flush it yearly; a tankless wants descaling on a schedule too.
My Annandale water heater sits beside the furnace. Does that change the flush?
Not the flush. Side by side on the lowest floor, with a floor drain nearby, is the easiest setup there is. If both burn gas we also look at how the water heater vents, since in houses this age it often shares a flue with the furnace.
Do you descale tankless heaters in Annandale?
Yes, $300 right now, regularly $350. Water this hard scales a tankless steadily, so it wants a descale on a schedule. If there are no service valves to hook up to, you get the price for adding them first.
How much does a water heater flush cost in Annandale?
$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
Book the flush, tank or tankless.
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 Annandale 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.