Stoney’s Plumbing · Laundry Room Odor Guide
A sewer smell near the washing machine is one of those problems that seems to come and go. The laundry room smells fine one day and like rotten eggs the next, often right after a load drains. Leesburg homeowners usually find that the odor has a plumbing cause they can track down: a dry or missing trap, a washer drain hose sealed too tightly into the standpipe, a blocked or missing vent, a failed air admittance valve, a slow drain, a dry floor drain nearby, or a problem further down the sewer line. Sometimes the smell is not sewer gas at all but a dirty washer, and occasionally a rotten-egg odor is a gas leak that needs very different handling. This guide explains how to tell those apart, what you can safely check yourself, what repairs typically cost, and when to call a plumber. Stoney’s Plumbing is a veteran-owned residential plumber at 574 Rockbridge Dr SE, Leesburg, VA 20175, serving Leesburg, Loudoun County, and Northern Virginia.
A sewer smell near a washing machine usually means sewer gas is getting past the trap in the washer’s drain. The most common causes are a standpipe trap that has dried out or siphoned empty, a washer drain hose pushed too far or sealed airtight into the standpipe, a clogged or missing plumbing vent, a failed air admittance valve, a partly clogged drain, or a dry floor drain nearby. A musty or mildew smell usually comes from the washer itself. If the odor smells like rotten eggs and you cannot rule out natural gas or propane, leave the house and call 911 and your gas company from outside.
Every price on this page is an educational range based on typical residential work, not a quote and not a price list from Stoney’s Plumbing. The cause in your home, the drain layout, and access decide what a specific repair costs.
Local context: Laundry rooms in Leesburg and Loudoun County homes are often on upper floors in newer houses, in basements or garages in older homes, and in hallway closets in townhomes. Each layout handles drainage and venting a bit differently, which affects where odors start. Drain odors often go hand in hand with slow drains, so our complete Leesburg drain cleaning guide is a useful companion. Call (703) 794-5592 or view Stoney’s Plumbing on Google Maps.
Quick answer: Natural gas and propane are given a rotten-egg odor so leaks can be noticed, and sewer gas can smell similar. If you smell rotten eggs near a gas dryer, water heater, or furnace and you are not sure of the source, treat it as a possible gas leak: leave the house, avoid switches and flames, and call 911 and your gas company from outside.
Many laundry rooms hold a gas dryer, and many sit next to a gas water heater or furnace. That puts gas appliances a few feet from the washer drain, which is exactly where a sewer smell usually starts. Utilities add an odorant to natural gas that smells like rotten eggs or sulfur. Sewer gas often contains hydrogen sulfide, which has a similar rotten-egg smell. In the moment, the two can be hard to tell apart.
Washington Gas, which serves much of Northern Virginia, publishes natural gas safety guidance that tells customers what to do if they smell gas. The core advice is consistent across utilities: do not use light switches, phones, or anything that could make a spark inside the house; do not try to find the leak yourself; leave the building; and call 911 and the gas company once you are a safe distance away. Homes on propane should call their propane supplier as well.
Even with those clues, if you have any doubt, put safety first and let the gas company check. A false alarm is far better than guessing wrong. Our guide to gas line plumbing and gas safety in Leesburg covers gas leak warning signs and what happens after the utility makes a home safe.
The low levels of sewer gas that drift out of a dry household trap are mainly an odor nuisance, though some people get headaches or nausea from it. Higher concentrations are a different matter. The OSHA overview of hydrogen sulfide explains that the gas is toxic and flammable at higher levels, collects in low, enclosed spaces like sewers and pits, and can dull the sense of smell so a person stops noticing it. That last point matters at home too: a smell that seems to fade while you stand in the room is not proof the source has stopped. Ventilate the space, avoid lingering, and get the cause fixed rather than masking it.
Quick answer: A washer drains into a vertical pipe called a standpipe, which leads to a U-shaped trap that holds water. That water plug blocks sewer gas. A vent lets air into the system so draining water does not suck the trap dry. If the trap, the vent, or the hose connection fails, sewer gas can escape.
Most washing machines in Leesburg homes drain into a standpipe, a vertical pipe usually about two inches in diameter, either standing open behind the washer or inside a recessed laundry box in the wall. The washer’s drain hose hooks into the top of the standpipe. Below it is a P-trap, the curved section of pipe that holds a few inches of water after each drain. That water is the barrier between the room and the sewer.
The third piece is the vent. Every trap needs a vent nearby that connects to the plumbing vent system, which usually exits through the roof. When a large volume of water rushes down a drain, it pulls air behind it. If the vent works, air comes in through the vent. If the vent is blocked or missing, the rushing water can pull the water out of the trap instead, leaving the trap empty and the room open to sewer gas.
Plumbing codes adopted in Virginia, administered through the Virginia Department of Housing and Community Development, set rules for standpipe height, trap location, and venting. The model provisions generally call for a standpipe that extends roughly 18 to 42 inches above its trap, a trap that sits a short distance above the floor, and a vent connection within a set distance of the trap. Exact requirements depend on the code edition and local amendments, so a plumber will check what applies to your home.
When any part of that system is missing, damaged, or installed incorrectly, odors follow. The good news is that most of these problems are fixable without major construction.
Quick answer: A rotten-egg or sewage smell usually points to sewer gas from the drain. A musty, mildew, or sour-laundry smell usually comes from the washer’s gasket, drum, or dispenser. A burning smell points to the dryer or an electrical issue. The type of smell narrows the search.
| What it smells like | Likely source | First step |
|---|---|---|
| Rotten eggs or sulfur near a gas appliance | Possible natural gas or propane leak | Leave the house; call 911 and the gas company from outside |
| Rotten eggs or sewage at the drain | Sewer gas from a dry trap, vent problem, or hose seal | Check the standpipe, trap, and hose connection |
| Musty, mildew, or damp laundry | Washer gasket, drum, dispenser, or drain pump filter | Clean the washer and leave the door open to dry |
| Sour or stagnant water | Standing water in the washer, drain pump filter, or a slow drain | Clean the pump filter and check drainage |
| Burning or hot dust | Dryer lint buildup, motor, or electrical problem | Stop using the dryer and have it checked |
| Sewage smell plus slow drains elsewhere | Main drain or sewer line restriction | Call a plumber for drain and camera inspection |
Front-load washers deserve a special mention. Their rubber door gasket traps moisture, lint, and detergent residue, and a closed door keeps the drum damp. The result is a sour or musty odor that many people describe as smelling like sewage. If the smell is strongest when you open the washer door, start there before assuming a plumbing problem.
Quick answer: If the trap under the standpipe loses its water, sewer gas comes straight up the pipe. Traps dry out from evaporation when a laundry room goes unused, or they get siphoned empty when the washer drains with too much force or a poor vent. A missing trap is also possible in older or improperly altered laundry plumbing.
A trap holds only a small amount of water, and in a warm, dry laundry room that water slowly evaporates. Homes where the washer sits idle for weeks, such as vacation homes, homes where someone travels for work, or homes with a second laundry hookup that is rarely used, can lose the trap seal entirely. The fix is simple: pour a few quarts of water down the standpipe. If the smell goes away and stays away while the washer is used regularly, evaporation was the cause.
Siphoning is the more common culprit in active laundry rooms. Modern washers pump water out quickly. A large slug of water dropping down the standpipe can pull the trap water along behind it, especially if the vent is restricted or the trap is too far from its vent. When that happens, the smell shows up right after the washer finishes draining, which is a strong clue.
In some homes, the standpipe connects to the drain with no trap at all, or with an S-trap, which is prone to siphoning and is not permitted for new work under modern codes. This often shows up where a laundry area was added or moved during a renovation without a permit. A plumber can install a proper P-trap and vent connection. If the work involves opening walls or moving drains, it may need a permit through the Loudoun County building permits office or the relevant town.
A standpipe that is too short can overflow when the washer pumps out. One that is too tall can be hard for the washer pump to push water into and can contribute to siphoning patterns that pull the trap. Standpipe height also interacts with the washer’s own instructions, which often specify a minimum and maximum drain height. A plumber can check whether the standpipe is in a workable range for your washer.
Quick answer: The washer drain hose should hang loosely into the standpipe with an air gap around it. If the hose is pushed too far down, taped in place, or sealed with foam or a rubber plug, the washer can siphon the trap dry or push sewer air back out. Pulling the hose up and leaving the opening unsealed often fixes the smell.
It is natural to want to seal the gap around the drain hose when a laundry room smells. Many homeowners stuff a rag, foam, or duct tape around the hose where it enters the standpipe, hoping to block the odor. That usually makes things worse. The standpipe is designed to be open at the top so that air can move freely as the washer drains. Sealing it can turn the hose and standpipe into a siphon that pulls water out of the trap.
Pushing the hose too far down the standpipe causes a similar problem. Most washer manufacturers specify how far the hose should go into the standpipe, often only several inches, and many provide a U-shaped hose guide to hold it at the right depth. If the hose reaches down near the trap, it can siphon water from the washer drum back into the drain and pull the trap empty.
If the smell disappears after the hose is set correctly and the trap is refilled, you may not need anything more. If it returns after the next few loads, look at the vent.
Quick answer: Vents let air into the drain system so traps stay full. When a vent is clogged by leaves, nests, debris, or ice, or when a laundry drain was installed without a proper vent, draining water pulls the trap dry and sewer gas escapes. Gurgling drains are a common companion symptom.
Plumbing vents are the pipes that poke up through your roof. They connect to the drain lines inside the walls and let air in and out so water can flow smoothly. A home’s vent system also carries sewer gas up and away from living spaces, which is why you should never see a vent end inside an attic or under a deck.
When a vent is restricted, the drain system has to find air somewhere else. Often it pulls it through the nearest trap. You may hear gurgling in the laundry sink, a nearby bathroom sink, or a tub drain when the washer drains. That gurgle is air bubbling through a trap, and each bubble can carry water out until the trap seal is lost.
Clearing a roof vent involves climbing onto the roof, which is a fall risk and best left to a professional. A plumber can run a cable or water down the vent from above, or confirm with a camera that the vent connects where it should. If the laundry drain has no vent, the options are running a new vent pipe or, where the code allows, installing an air admittance valve.
Quick answer: An air admittance valve is a one-way valve that lets air into a drain when water flows and closes to keep sewer gas in. Many laundry boxes and basement laundry drains use them. When the seal inside sticks open, sewer gas leaks into the room. Replacement is usually a small job.
Air admittance valves, often called AAVs or by brand names, are small plastic devices that screw onto a vent pipe inside a wall cavity, under a sink, or inside a recessed laundry box. They open under negative pressure, letting air into the drain as water rushes down, and gravity closes them again. They are used where running a full vent pipe to the roof is impractical, and building codes allow them in many situations with conditions on location and access.
AAVs have a moving seal, and over years that seal can stiffen, warp, or get stuck open with dust and lint, which a laundry room has plenty of. A stuck-open AAV lets sewer gas escape whenever there is any pressure in the drain. A stuck-closed AAV acts like a blocked vent and lets traps siphon dry. Either way, the result is odor.
Look inside the laundry box behind the washer, under a nearby laundry sink, and in any small access panel in the wall near the washer. An AAV usually looks like a short plastic cylinder or cap on top of a vertical pipe. If you find one and the smell is strongest near it, the valve is a likely suspect. AAVs must stay accessible and must not be sealed inside a wall with no way to reach them, because they eventually need replacement.
Quick answer: Lint, detergent residue, fabric softener, and hair build up inside laundry drains over time. That sludge holds bacteria that smell, slows drainage, and can make the standpipe back up or overflow. Professional drain cleaning removes the buildup.
Laundry drains carry more lint and soap residue than almost any other drain in the house. Powdered detergents can clump, liquid fabric softener can coat the pipe walls, and lint from synthetic fabrics forms a felt-like mat. Over months and years, that buildup narrows the pipe and becomes a home for bacteria that produce sulfur odors as they break down organic material.
A partly clogged laundry drain often announces itself with a standpipe that fills close to the top while the washer pumps out, water appearing on the floor behind the washer, or a nearby floor drain or laundry sink gurgling or backing up. Standing dirty water in the standpipe smells, even if the trap and vent are fine.
Chemical drain openers are a poor fit for laundry drains. They rarely clear lint mats, they can damage older pipes, and they make the work riskier for anyone who opens the drain afterward. A mechanical cable or, in some cases, hydro jetting is the usual approach. Our guide to small plumbing repairs in Leesburg explains which drain problems are reasonable DIY projects and which need a professional.
A lint trap or mesh filter on the washer drain hose, available at most hardware stores, catches a surprising amount of debris before it reaches the pipe. It needs regular cleaning but can prevent a lot of buildup.
Quick answer: A sewer smell in the laundry room does not always come from the washer drain. Basement floor drains, unused laundry sinks, utility tubs, rarely used showers, and water heater pan drains can all have traps that dry out and let sewer gas in.
Many basement and garage laundry areas have a floor drain nearby. Floor drains have traps just like sinks, and because they rarely get water, those traps often dry out. A dry floor drain trap a few feet from the washer can make it seem like the washer is the source. Pouring a gallon or two of water into the floor drain refills the trap. Some plumbers add a little mineral oil on top of the water to slow evaporation, or recommend a trap seal device or trap primer for drains that are rarely used.
The same goes for a laundry sink that nobody uses, a basement bathroom that sits empty, or a water heater drain pan that ties into a drain line. Walk the area and check every opening within a few rooms of the laundry space. A smell that seems to come from the washer can easily come from a dry trap next door.
Odors that appear in several rooms at once, or that come with slow drains in more than one fixture, suggest the problem is further down the line. Our overview of leaks, drains, toilets, and other common Leesburg plumbing problems covers how these symptoms connect across the house.
Quick answer: If the sewer smell comes with slow drains throughout the house, gurgling toilets when the washer drains, or water backing up into a floor drain or tub, the main drain or sewer line may be partly blocked or damaged. A camera inspection shows what is happening inside the line.
A washing machine sends a large volume of water down the drain in a short time, often the biggest single surge your plumbing sees. If the main drain or the sewer lateral to the street is partly blocked by roots, grease, sagging pipe, or a broken section, that surge has nowhere to go. Water backs up into the lowest fixtures, often a basement floor drain or shower, and air pushed ahead of it can force sewer gas out of traps.
Warning signs that point beyond the laundry drain include sewage odors in several rooms, toilets that gurgle or bubble when the washer drains, slow drains on more than one floor, and water appearing at a floor drain during a wash cycle. Homes served by public sewer in Loudoun County generally make the homeowner responsible for the sewer lateral from the house to the connection at the public main, with specifics depending on the utility and property. Homes on septic systems in rural parts of the county have their own set of causes, including a full tank or a struggling drain field.
Who to call first depends on where the problem sits. If sewage is backing up in several homes on your street, or you see an overflowing manhole or cleanout at the public main, contact your sewer provider. Homes inside the Town of Leesburg are served by the town utility, and many other homes on public sewer in the county are served by Loudoun Water. If the problem is only in your house, the cause is almost always in your own drain or lateral, and a plumber is the right call. A cleanout near the foundation, if your home has one, gives a plumber a quick way to see whether the backup is inside the house or further out.
Our guide to sewer line repair, homeowner responsibility, and warning signs in Leesburg covers lateral ownership, camera inspection, and educational repair costs in detail.
If your laundry room smells like sewage, call Stoney’s Plumbing at (703) 794-5592. We will check the standpipe, trap, hose connection, vent, and nearby drains, explain what we find in plain terms, and give you a written scope and price before any work begins. If the smell could be gas, leave the house and call 911 and your gas company first.
Quick answer: Washers can smell bad on their own. Front-loaders trap moisture in the door gasket, residue builds up in detergent dispensers, and drain pump filters collect lint and standing water. A monthly cleaning cycle, a wiped gasket, and an open door between loads solve most washer odors.
Before calling a plumber, it is worth ruling out the washer. Stand next to the machine and smell the open drum, the door gasket, and the detergent drawer. If the odor is strongest there, rather than at the standpipe behind the machine, the washer is the likely source.
The flexible rubber gasket around a front-loader’s door folds back on itself, creating a pocket that holds water, lint, hair, and detergent. Mold and bacteria grow there quickly, especially when the door stays shut between loads. Pull back the gasket and look inside; dark spots or slimy residue are common. Wiping it with a cloth and a mild cleaning solution, running the washer’s cleaning cycle, and leaving the door ajar to dry make a large difference.
Many front-loaders have a small access door near the bottom front that hides the drain pump filter. It catches coins, lint, and small items, and it holds a small amount of standing water. Left alone for months, that water and debris turn sour. The owner’s manual explains how to drain and clean it; keep towels and a shallow pan handy.
Top-loaders tend to smell less, but residue can build up under the agitator and in the outer tub. Using more detergent than needed, washing mostly in cold water, and heavy fabric softener use all leave more residue behind. High-efficiency washers are designed for HE detergent in small amounts; extra soap does not clean better and feeds odor-causing buildup.
If a thorough washer cleaning does not change the smell, or if the odor is clearly coming from the wall behind the washer, the plumbing is the next place to look.
Quick answer: Refill every nearby trap with water, check that the washer hose is not sealed or pushed too deep, clean the washer gasket and pump filter, listen for gurgling when the washer drains, and note when the smell appears. Leave roof vents, drain disassembly, and sewer work to a plumber.
A few simple checks can solve the problem outright or give a plumber the information to fix it quickly.
Pour two or three quarts of water down the washer standpipe, any nearby floor drain, the laundry sink, and any rarely used fixture in the area. If the smell clears up for several days, a dry trap was at least part of the problem.
Pull the washer out enough to see the standpipe. Remove anything sealing the hose into the pipe, set the hose at the depth the manual recommends, and secure it so it cannot slip out.
Wipe the door gasket, clean the detergent dispenser, drain and clean the pump filter, and run a cleaning cycle. Leave the door open between loads for a week and see whether the smell changes.
Stand near the washer while it drains. Note whether water rises close to the top of the standpipe, whether nearby sinks or toilets gurgle, and whether the smell appears during or right after the drain. These details point toward clogs, vent problems, or siphoning.
Write down when the smell shows up: after a wash, after the room sits unused, during windy weather, or after heavy rain. A pattern helps a plumber narrow down the cause and avoids unnecessary work.
If you are deciding whether a laundry drain problem is a reasonable DIY project or work for a professional, our guide comparing DIY repairs, handymen, and licensed plumbers in Leesburg explains where the lines usually fall. In Virginia, plumbing work for hire is licensed through the Department of Professional and Occupational Regulation license lookup, which lets you confirm a contractor’s license before work begins.
Quick answer: Many fixes are inexpensive: refilling traps and resetting the hose cost nothing, and replacing an air admittance valve or correcting a standpipe trap is usually a few hundred dollars. Adding a vent, replacing a laundry box, or repairing a sewer line costs more.
The ranges below are educational, based on typical residential work in Northern Virginia in 2026. They are not quotes and not Stoney’s Plumbing prices. Access, wall finishes, drain layout, and permit requirements decide the real cost.
| Repair | Typical range (educational) | What moves the price |
|---|---|---|
| Refill traps, reset washer hose, clean washer | DIY: about $0–$30 | Cleaning supplies, hose guide or lint filter |
| Air admittance valve replacement | About $150–$450 | Access, wall or laundry box opening |
| Standpipe or P-trap correction | About $200–$700 | Pipe material, wall access, trap height changes |
| Laundry drain cleaning (cable) | About $150–$450 | Access point, length of clog, buildup type |
| Drain camera inspection | About $200–$500 | Access, line length, whether combined with cleaning |
| Roof vent clearing | About $200–$600 | Roof pitch, height, number of vents |
| Recessed laundry box replacement | About $300–$900 | Wall repair, valve replacement, drain changes |
| Adding a new vent pipe | About $500–$2,000+ | Route to existing vent or roof, walls opened, permit |
| Floor drain trap primer or trap seal | About $50–$500 | Simple insert versus plumbed primer |
| Sewer line repair or replacement | About $1,500–$12,000+ | Method, depth, length, landscaping and hardscape |
Drywall, tile, and paint repair after opening a wall are often separate line items. Ask whether a proposal includes them. For a broader look at how local plumbing prices are built, see our guide to what plumbing repairs cost in Leesburg in 2026, and for the bigger picture of which services matter most, our comparison of water heater, drain, leak, and sewer services for Leesburg homes.
Quick answer: Call a plumber when the smell returns after you refill traps and fix the hose, when drains gurgle or back up, when water appears on the floor during a wash, when an air admittance valve or vent is involved, or when several rooms smell. If the smell could be gas, call the gas company first.
Most laundry odor problems are not urgent, and it is reasonable to plan the visit at a convenient time. Our guide to the best time to schedule plumbing repairs in Leesburg explains how to plan non-urgent work. If sewage is actively backing up into the home, our Leesburg homeowner guide to urgent plumbing problems explains what to do first. To get a sense of how long typical fixes take, see plumbing repair time frames in Leesburg.
Quick answer: Run water into rarely used drains every couple of weeks, keep the washer hose set correctly, use a lint filter on the drain hose, use the right amount of HE detergent, clean the washer monthly, and have vents and air admittance valves checked when other plumbing work is done.
Laundry rooms often get updated alongside other fixtures. If you are planning a refresh, our guide on replacing old plumbing fixtures in Leesburg homes explains which items wear out first, and our article on how plumbing repairs can affect home value covers why buyers and inspectors pay attention to odors and drain problems.
Quick answer: These examples show how the same rotten-egg smell can come from very different causes, from a dry trap to a failing sewer line. They are illustrations, not case studies.
A family with a basement laundry notices a sewer smell after a dry summer. The washer standpipe is fine, but the floor drain beside it has no water in its trap. Pouring water in solves the problem, and a simple trap seal insert keeps it from recurring. Cost: under $50.
In a townhome, the washer hose has been taped tightly into the standpipe. The smell shows up right after every load. Removing the tape and setting the hose at the right depth with a hose guide stops the siphoning. Cost: nothing beyond a few minutes.
An upstairs laundry in a newer single-family home smells faintly of sewage most of the time. Inside the recessed laundry box is an air admittance valve coated in lint, stuck partly open. Replacing it clears the smell. Educational range: about $150 to $450.
Every time the washer drains, the bathroom sink next door gurgles and the laundry room smells for an hour. A plumber finds the roof vent partly blocked with debris. Clearing it lets the drains breathe and the traps stay full. Educational range: about $200 to $600.
A homeowner who bought an older house with a garage laundry finds that a previous owner connected the standpipe straight into a drain line with no trap and no vent. A plumber installs a proper P-trap and an air admittance valve where permitted. Educational range: about $350 to $1,000 depending on access and permit needs.
A homeowner notices sewage odors and water in the basement shower drain whenever the washer runs. A camera inspection shows tree roots in the sewer lateral. Cleaning restores flow short term, and the family plans a lateral repair. Educational range: drain cleaning and camera about $350 to $950; repair several thousand dollars or more depending on method.
In every example, the fix came from finding where the sewer gas was getting in. Masking the smell with air fresheners or sealing the standpipe would have hidden the symptom and left the cause in place.
Quick answer: Stoney’s Plumbing is a veteran-owned residential plumber at 574 Rockbridge Dr SE, Leesburg, VA 20175. Call (703) 794-5592.
We help Leesburg and Loudoun County homeowners find and fix laundry room sewer smells: correcting standpipes and traps, replacing air admittance valves, clearing laundry drains, checking vents, and inspecting main drains and sewer lines with a camera when the problem runs deeper. We find the source before we recommend a repair, explain what we see, and give you the scope and price in writing before we start. The educational ranges on this page stay separate from the price you get after we see the job.
Visit Stoney’s Plumbing online or find us on Google Maps. Address: 574 Rockbridge Dr SE, Leesburg, VA 20175. Service conversations commonly cover Leesburg, Loudoun County, Ashburn plumbing repairs, plumbing help in Sterling, Lansdowne and River Creek plumbers, Aldie, South Riding, Purcellville plumbing service, and Hamilton and Round Hill plumbing.
A sewer smell near a washing machine usually means sewer gas is getting past the trap in the washer drain. Common causes are a dry or siphoned trap, a drain hose sealed or pushed too far into the standpipe, a clogged or missing vent, a failed air admittance valve, a partly clogged drain, or a dry floor drain nearby.
They can smell alike. Natural gas and propane carry an added rotten-egg odorant, and sewer gas often contains hydrogen sulfide. If the smell is near a gas dryer, water heater, or furnace and you cannot rule out gas, leave the house, avoid switches and flames, and call 911 and your gas company from outside.
A smell that shows up right after draining usually points to siphoning. The rush of water down the standpipe pulls the water out of the trap, often because the vent is restricted, the hose is sealed into the standpipe, or the hose reaches too far down. With the trap empty, sewer gas comes up the pipe.
Yes. The water in a trap is the barrier that blocks sewer gas. In a laundry room or basement that goes unused for a while, that water evaporates. Pouring a few quarts of water down the standpipe and any nearby floor drain refills the traps and often clears the smell.
No. The standpipe is meant to be open at the top so air can move as the washer drains. Sealing the hose in with tape, foam, or a rag can create a siphon that empties the trap. Set the hose at the depth the washer manual recommends and secure it with a hose guide instead.
An air admittance valve is a one-way valve that lets air into a drain when water flows and closes to keep sewer gas in. They are common inside laundry boxes and under laundry sinks. If the internal seal sticks open from age, dust, or lint, sewer gas can leak into the room. Replacement is usually a small job.
Yes. Vents let air into the drain system so traps stay full. When a roof vent is blocked by debris, nests, or frost, draining water pulls air through the nearest trap instead, often with a gurgling sound, and the trap can lose its seal. Clearing roof vents is best left to a professional.
Smell the open drum, door gasket, and detergent drawer. A musty, mildew, or sour smell strongest at the washer usually comes from residue in the gasket, dispenser, or drain pump filter. Cleaning those parts, running a cleaning cycle, and leaving the door open between loads usually solves it.
The small amounts that drift from a dry household trap are mainly an odor problem, though some people get headaches or nausea. Hydrogen sulfide is toxic at higher concentrations and can dull the sense of smell, so ventilate the area, keep people out if anyone feels unwell, and fix the cause rather than masking it.
As educational ranges, refilling traps and resetting the hose cost little or nothing, air admittance valve replacement often runs about $150 to $450, standpipe or trap corrections about $200 to $700, and drain cleaning about $150 to $450. New vents, laundry box replacement, or sewer line repair cost more. These are not quotes.
Yes. A washer sends a large surge of water down the drain. If the main drain or sewer lateral is partly blocked or damaged, that water can back up into a floor drain or shower and push sewer gas out of traps. Sewage odors in several rooms, gurgling toilets, and slow drains on more than one floor point to the main line.
Simple fixes like replacing an air admittance valve usually do not need a permit, but adding a new vent, moving a drain, or rebuilding a standpipe and trap inside a wall may. Requirements depend on the scope and whether you are in a town or unincorporated Loudoun County. A licensed plumber typically handles any permit.
Call a plumber when the smell returns after you refill traps and correct the hose, when drains gurgle or back up during a wash, when water pools behind the washer, when several rooms smell, or when an air admittance valve or vent is involved. If the smell could be gas, call the gas company first.
Stoney’s Plumbing is a veteran-owned residential plumber at 574 Rockbridge Dr SE, Leesburg, VA 20175. Call (703) 794-5592. We serve homeowners in Leesburg, Loudoun County, and nearby Northern Virginia communities.
If your laundry room smells like sewage, call Stoney’s Plumbing at (703) 794-5592. We will check the standpipe, trap, vent, and nearby drains, explain what is letting sewer gas in, and give you a written scope and price before any work begins. The ranges on this page help you plan. Finding the actual source is what makes the smell stay gone.
574 Rockbridge Dr SE, Leesburg, VA 20175 · Serving Leesburg, Loudoun County & Northern Virginia
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