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In Lorton, 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 Lorton are rated 5.0 stars across 1,130 reviews and work under Virginia Class A contractor license 2705192276. Water pressure and PRV replacement in Lorton, Laurel Hill and Lorton Valley, where houses from the 2000s are reaching the age their valve and tank wear out. 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.
5.0 stars across 1,130 reviews
New copper supply piping with red-handled shutoff valves, installed and tagged by one of our plumbers.
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Licensed and insuredVirginia Class A contractor #2705192276
24/7 emergency serviceWe answer day or night, and we will tell you honestly when we can get there.
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What it costs
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 Lorton
The big subdivisions here are not old. Laurel Hill went up between 2003 and 2009, Lorton Valley North in 2004 to 2006, and over four in ten homes in the ZIP date from 2000 or later. Every one of them was built with a pressure reducing valve and, in most cases, a thermal expansion tank, because by then the code expected both. So the question in Lorton isn’t whether there’s a valve. It’s whether the original has started to slip at fifteen to twenty years.
The giveaway in these houses is rarely a bang in the walls. It’s a water heater relief valve that starts to weep in warm weather, a washer that goes through fill valves, or a shower that’s stronger in the morning than at dinner. Fairfax Water answers for the main, and the valve inside your line is yours. With a brass valve this age we read the gauge cold, then again after the heater has run.
The tank matters as much as the valve. An expansion tank that has lost its air charge looks fine from the outside, and a house with a new valve and a dead tank still drips at the relief valve. Pressing the little air stem on the tank takes a second: air means it’s holding, water means it’s finished. We check it on the same visit as the valve.
Pohick Estates, east of the Lorton town center, is the other end of Lorton. Those 1957 to 1972 houses are mostly split foyers, and the water line often comes in on the lower level, behind the stairs, which is a different search from a new basement utility room. A house that old may have no valve at all, or one added after a plumber’s visit. Townhouse rows in between have their own valve in each unit.
Neighborhood by neighborhood
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 |
|---|---|---|---|---|
| Lorton | 2001 | single-family houses, about 4 in 10 | gas, about 7 in 10 | A reducing valve and an expansion tank. |
| Newington | 1981 | townhouses, about 6 in 10 | electricity, about 6 in 10 | The builder’s original reducing valve, worn. |
| Laurel Hill | 2002 | single-family houses, about 4 in 10 | gas, about 8 in 10 | A reducing valve and an expansion tank. |
| Mason Neck | 1973 | single-family houses, nearly all | electricity, about 6 in 10 | An old gate valve, often no reducing valve. |
By the numbers
From the Census Bureau’s 2020 to 2024 survey. Median year built and heat count owner-occupied homes only.
ZIP 22079 as a whole: every Lorton address. Most of Newington, in the table, has Springfield mail.
The signs
If pressure is higher at night and early morning, when nobody has been drawing water, and drops once the house wakes up, the valve is letting the street’s pressure through when the house is still. That pattern points at the valve, not the supply.
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.
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 Lorton?
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Choosing who fixes it
Questions to ask anybody who quotes you a valve, us included.
In a Lorton house from the 2000s, the valve and the tank wear on the same clock. A plumber who reads the gauge and taps the tank is fixing the whole problem, not one half of it.
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.
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.
From our Google reviews
5.0 stars across 1,130 reviews. Read them on our reviews page.
Polite, courteous, professional, and without any hard sell pressures.
Where we work
Next door to Lorton: Springfield, Burke, Annandale, Falls Church and Oakton.
Questions
It could be. Brass valves often run well past fifteen years, but they drift, and a house this age that drips at the water heater relief valve is worth a reading. If the gauge sits near 60 psi cold and rises overnight, the valve is on its way out.
Look near the main shutoff, usually on the lower level behind the stairs or in the utility room with the water heater. A bell-shaped brass valve with a bolt on top is the one. If it isn’t there, the house may not have one.
$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.
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
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 Lorton 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.