If your laundry room smells like sewage, you are not alone. This issue is surprisingly common in homes with floor drains, washing machine hookups, or older plumbing systems.
A sewage smell in the laundry room can be unpleasant, but it may also point to a plumbing problem that should not be ignored. The good news is that many causes are easy to identify early with the right approach.
Let's look at what may be causing the odor and what you can do about it.
What Causes a Sewage Smell in a Laundry Room?
A sewage-like odor usually means sewer gases are escaping into your home. These gases should stay inside your plumbing system and exit through roof vents.
When something interrupts that process, smells can build up quickly. If your laundry room smells like sewage, it is often related to traps, drains, or venting issues.
Dry or Empty Drain Traps
One of the most common causes is a dry P-trap. The P-trap is the curved pipe under a drain that holds water. That water blocks sewer gases from coming back up.
If a floor drain or utility sink is rarely used, the water can evaporate.
This leaves an open path for odors, leading to a strong sewage smell in the laundry room.
What to do: Run water into the drain for a few seconds to refill the trap.
Clogged or Dirty Washing Machine Drain
Lint, detergent residue, and debris can build up in the washing machine drain line over time. This buildup can trap bacteria and cause foul smells.
Sometimes the odor is mistaken for sewer gas when it is actually coming from organic buildup.
Regular plumbing maintenance can help prevent this issue from developing.
Blocked Vent Pipe or Poor Venting
Your plumbing system relies on vent pipes to balance air pressure and release sewer gases safely outside.
If a vent becomes blocked, gases may be forced back through drains instead.
This is another major reason a laundry room smells like sewage, especially after running the washer.
Signs of venting trouble include:
- Gurgling sounds
- Slow drainage
- Odors that come and go
Sewer Line or Drain Line Problems
A persistent sewage odor may point to a deeper issue, such as a partial sewer line blockage or damage in the drain system.
If wastewater is not flowing correctly, gases can collect and escape through nearby drains.
This situation should be inspected quickly, as it can worsen over time.
Loose or Damaged Drain Connections
Laundry rooms often have multiple plumbing connections in tight spaces. If a pipe joint becomes loose or a seal fails, sewer gases may leak out.
Even a small gap can cause noticeable odor.
Professional plumbing maintenance can identify these hidden leaks before they grow into larger problems.
Mold or Moisture That Mimics Sewage Odors
Not every bad smell is sewer gas. Damp areas behind washers or near drains can lead to mold growth.
Mold odors can sometimes resemble a sewage smell, especially in humid laundry rooms.
Check for standing water, damp drywall, and musty air near baseboards.
How to Get Rid of Sewage Smells in the Laundry Room
If you notice a sewage smell in the laundry room, start with a few simple steps:
- Run water into unused drains
- Clean the washer drain and nearby pipes
- Check for slow drainage or gurgling
- Inspect visible connections for leaks
- Schedule an inspection if odors persist
Ongoing plumbing maintenance is one of the best ways to keep these odors from returning.
When to Call a Plumbing Professional
If the smell continues after basic troubleshooting, it may be time to get expert help.
A licensed plumber can inspect vents, traps, drain lines, and sewer connections to find the true source. This is especially important if your laundry room smells like sewage repeatedly or the odor becomes stronger.
Ignoring sewer gas problems can lead to bigger plumbing repairs later.
Laundry Room Plumbing Help from J. Blanton Plumbing
If you are dealing with ongoing laundry room odors or suspect a hidden drain issue, J. Blanton Plumbing can help.
Our team provides reliable laundry room plumbing services, including drain inspections, vent troubleshooting, and preventative plumbing maintenance to keep your home's system working properly.
Reach out anytime to schedule a professional evaluation and restore fresh, clean air in your laundry space.
J. Blanton Plumbing is a leading plumbing service provider in Chicago, specializing in water heater installation, plumbing repairs, drain cleaning, and whole-home plumbing solutions. With over 30 years of industry experience, our licensed technicians create expert resources to help homeowners understand their plumbing options and maintain long-lasting, dependable systems.
