The pipes knock when the dishwasher shuts off
That bang is water hammer, the exact problem the Town’s standards name, and high pressure makes it worse. A gauge reading tells you in a minute whether it’s the valve.
Herndon, Virginia
Water pressure and pressure reducing valve replacement in Herndon.
In Herndon, a pressure reducing valve replaced is $500 to $1,000. Call SwiftPro, rated 5.0 stars across 1,130 reviews, at (703) 997-9757, 24 hours a day, 7 days a week.
SwiftPro’s plumbers in Herndon are rated 5.0 stars across 1,130 reviews and work under Virginia Class A contractor license 2705192276. Water pressure and PRV replacement in Herndon, Town or county side: the Town’s own 80 psi rule, the valve that’s yours, and a gauge on your hose bib. If the pressure is fine and the trouble is a hidden leak, finding it is $200 to $500. A main shutoff valve is priced at your house, once we’ve seen the pipe it’s on.
- A gauge reading before the price
- Our own licensed plumbers
- Set and tested before we leave
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New copper supply piping with red-handled shutoff valves, installed and tagged by one of our plumbers.
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What it costs
What a pressure reducing valve costs in Herndon.
From the same price book as our plumbing price list: the valve, the fittings, setting it with a gauge and checking the house afterward. More on what causes it in our low water pressure guide.
Pressure reducing valve replacement
$500 to $1,000
Leak detection
$200 to $500
Prices checked .
Where you land in the range is mostly where the valve sits and what it’s attached to: a valve right at the main shutoff in an open basement is the easy end, one behind a finished wall or on corroded pipe is the other.
When a new valve brings the pressure down, the water heater can no longer push its expansion back into the street, so we check for an expansion tank on the same visit and tell you if the house needs one.
What’s different in Herndon
Herndon wrote its 80 psi line into its own water standards, and the valve it asks for is the owner’s.
Herndon runs its own water system, and its design standards spell pressure out in numbers. The Town aims for at least 40 psi at your connection on a busy day. Where a connection sees more than 80, the owner puts a regulating valve in the house plumbing, and the standards say why: to stop water hammer and cut how much water the house uses. The Town’s pipe ends at the meter, so that valve is on you.
The same standards admit the ground matters, and Herndon’s rolls, from the blocks off Elden Street down toward the stream valleys. No Town page lists a pressure for your street, so we don’t guess one. We read yours with a gauge at an outside spigot, still and then flowing, and you see the number first. Questions about the supply itself go to Town Public Works at (703) 435-6860.
Herndon splits almost evenly between houses built before 1980 and houses from the 80s and 90s. A 1970s house may have no reducing valve, or one nobody has touched. A builder valve from 1990 has had decades to drift upward. One more detail in the Town’s standards: every meter gets a backflow check. That keeps water from running back to the street, and it also leaves the heat expansion from your water heater nowhere to go but your pipes, so the expansion tank matters more than people think.
On the county side, in Franklin Farm, Floris and McNair, Fairfax Water serves the house and promises only a floor at the main, with the valve on your side of the meter yours. A third of homes there went up since 2000, so most have a valve and a tank. In the condo buildings off Sunrise Valley Drive, one building valve can serve everyone, and the association owns it.
Neighborhood by neighborhood
What a pressure problem looks like across Herndon.
Census figures for the owner-occupied homes in each place, and what usually sits at the main shutoff in houses like them.
| Place | Median home built | Most homes are | Heated with | What’s usually at the main shutoff |
|---|---|---|---|---|
| Franklin Farm | 1985 | single-family houses, about 9 in 10 | electricity, about 5 in 10 | The builder’s original reducing valve, worn. |
| Herndon | 1981 | single-family houses, about 4 in 10 | electricity, about 6 in 10 | The builder’s original reducing valve, worn. |
| Dranesville | 1984 | single-family houses, nearly all | electricity, about 6 in 10 | The builder’s original reducing valve, worn. |
| McNair | 2003 | condo and apartment buildings, about 6 in 10 | gas, about 7 in 10 | A reducing valve and an expansion tank. |
| Floris | 1990 | single-family houses, about 8 in 10 | gas, about 6 in 10 | The builder’s original reducing valve, worn. |
| Hutchison | 1979 | townhouses, about 5 in 10 | electricity, about 7 in 10 | An old gate valve, often no reducing valve. |
| Sully Square | 2015 | condo and apartment buildings, about 6 in 10 | gas, about 6 in 10 | A reducing valve and an expansion tank. |
By the numbers
Herndon houses, by the numbers
From the Census Bureau’s 2020 to 2024 survey. Median year built and heat count owner-occupied homes only.
The Town of Herndon
Inside the town limits. Floris, Franklin Farm, McNair and Dranesville, on the Fairfax County side, are counted by the Census as places of their own.
- Median home built1981 Census
- Built before 1980about 4 in 10 Census
- Built since 2000about 2 in 10 Census
- Most homes aresingle-family houses, about 4 in 10 Census
- Heated withelectricity, about 6 in 10 Census
- Rentedabout 4 in 10 Census
- Houses from the 80s and 90s often came with a valve after the main shutoff, and many of those are original and worn.
- Many homes here are townhouses or condos. A townhouse usually has its own valve near the meter; in a condo building it may be the building’s, so the association is the first call.
The signs
When a Herndon house has a pressure problem.
The house is old enough that the valve is too
Many houses built on public water since the 1980s came with a valve right after the main shutoff. A lot of those are the originals, and a valve that old has usually stopped holding the pressure where it was set.
Pipes bang when a faucet shuts
A thud in the wall when the washer or a faucet closes is water hammer, and high pressure makes it worse. So does a toilet that keeps refilling, or faucets that drip no matter how many washers go in.
Need water pressure and pressure reducing valves in Herndon?
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Choosing who fixes it
How to pick who fixes water pressure in Herndon.
Questions to ask anybody who quotes you a valve, us included.
Did they read the pressure before they sold a valve?
A new reducing valve is $500 to $1,000. A plumber who quotes it without a gauge on your spigot is guessing. If pressure is fine and the bill is high, a hidden leak search is $200 to $500.
Did they put a gauge on it before the price?
A valve quoted without a pressure reading is a guess. Ask what the house reads now, static and with water running, and what they’ll set it to.
Did they ask about the water heater?
A new valve changes how the water heater handles expansion. The plumber who checks for an expansion tank is the one who saves you a dripping relief valve next month.
Two of our crew going over a work order before the day's calls.
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What our customers say.
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Questions
Water pressure questions from Herndon.
Will the Town of Herndon replace my pressure reducing valve?
No. The Town’s part ends at the meter’s outlet, and its standards put the valve in the building plumbing, on the owner. Inside town limits it’s done under the Town’s own plumbing permit.
My shower is weak upstairs. Is that the valve too?
Sometimes, if it’s stuck mostly closed. In a 1970s house it can be old pipe or a clogged fixture instead. Our guide to low pressure through the whole house walks through which is which, and the gauge settles it.
How much is a pressure reducing valve replacement in Herndon?
$500 to $1,000, with the valve, the fittings and setting it with a gauge in that number. Where you land depends on where the valve sits and the pipe it’s on.
What should my water pressure be?
Most houses run well somewhere around 50 to 70 psi. The Virginia Residential Code calls for a reducing valve once the street pressure tops 80 psi. We read it with a gauge on a hose bib so you know your own number.
Ready when you are
Find out what the pressure really is.
Call, or send the form at the top. We put a gauge on the house, show you the number, and you get the price in writing before any valve comes out.
SwiftPro Heating, Cooling & Plumbing
4230 Lafayette Center Dr N, Chantilly, VA 20151
44679 Endicott Dr, Suite 211, Ashburn, VA 20147
SwiftPro Plumber & Water Heaters
4200 Lafayette Center Dr, Suite N, Chantilly, VA 20151
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 Herndon and the rest of Northern Virginia. Virginia contractor license #2705192276. 5.0 stars across 1,130 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.