When you open the dishwasher after a wash cycle and smell a strange odor it means there is a problem underneath.
A dishwasher smells like sewage because sewer gases or dirty drain water are coming back into the unit. It is usually due to a dry or faulty trap, food buildup, or poor venting. It is a sign that something in the plumbing system is not working as it should.
Sewer gas can contain hydrogen sulfide which causes a rotten egg or sewage smell and should not be present inside homes. According to Health Canada sewer gas exposure at home can cause headaches, nausea, and in serious cases more harmful effects.
In this blog Blue Sea Plumbing will help you understand why your dishwasher stinks and what to do about it.
Key Takeaways
- A dishwasher that smells like sewage often points to a drain or vent issue.
- Cleaning helps but does not fix plumbing related dishwasher odors.
- Early repair lowers the risk of sewer gas entering your home.
- A professional inspection from Blue Sea Plumbing gives lasting results and peace of mind.
Why Does My Dishwasher Smell Bad?
A bad dishwasher smell can come from leftover food but a sewage smell is more serious. Food odors smell sour or greasy and stay inside the dishwasher. Sewer gas smells like rotten eggs and can spread through the whole kitchen. This kind of smell means air from the drain system is coming back up.
When a dishwasher smells like sewage it is a warning sign and not a cleaning problem. It shows that something is wrong with the drain setup or airflow. Cleaning tablets may cover the smell for a short time but they do not fix the real cause.
Plumbing problems need early care to protect your health and pipes. A professional inspection can find the issue before it gets worse. You can contact Blue Sea Plumbing for an inspection and a safe fix.
Common Reasons a Dishwasher Smells Like Sewage
Here is what you should know.
Dry or Improper P-Trap Connection
A P-trap holds water that blocks sewer gas from entering your home. If this trap dries out or is installed wrong sewer gas can move freely into the dishwasher. This is common in homes where the dishwasher is not used often.
When water sits unused it can evaporate from the trap. Once that seal is gone the smells travel back through the drain line. Running the dishwasher regularly can help but a loose or damaged trap needs a proper fix from a licensed plumber.
Clogged or Dirty Dishwasher Drain Hose
The drain hose carries dirty water away from the dishwasher. Over time food bits, grease, and soap residue can build up inside. This buildup causes slow drainage and creates a stinky dishwasher smell.
If you notice water backing up or dishes smelling bad after a wash the hose may be blocked. Our drain cleaning service can clear the blockage and restore proper flow.
Garbage Disposal Backflow
Many dishwashers connect to the same drain as the garbage disposal. If the disposal is dirty or clogged the waste can flow back into the dishwasher. This backflow causes a strong dishwasher stinks problem after each cycle.
Food stuck in the disposal breaks down and releases odor. If you connected to a garburator, understanding how it works can help prevent backflow and odor problems. Read our guide on how a garburator works and how it affects your kitchen plumbing.
Blocked Air Gap or Missing High Loop
An air gap or high loop stops dirty water from flowing back into the dishwasher. If the air gap is blocked or missing wastewater can return and create a smell from dishwasher.
Improper installation is a common cause in older homes. This issue does not fix itself and usually needs a plumber to correct the setup. Contact Blue Sea Plumbing if you think this may be the cause in your home.
Sewer Line or Venting Issues
If the smell keeps coming back the problem may be deeper in the plumbing system. Blocked vents or damaged sewer lines stop gases from escaping outdoors. Instead they push air back through fixtures like the dishwasher.
If you suspect a sewer line issue our camera drain and sewer inspection service can find the exact location of the problem without digging up your floors. For more serious damage our sewer line repair and replacement team can fix the issue properly.
How to Get Rid of a Dishwasher That Stinks
Start With a Deep Clean
Start with the filter because trapped food often causes a stinky dishwasher even when dishes look clean.
Remove the filter and rinse it with warm water and mild soap.
Check the spray arms for debris that blocks water flow and clear any build up you find.
Pour one cup of white vinegar into the bottom of the empty dishwasher and run a hot cycle. This helps break down grease and soap residue inside the drum.
Follow with half a cup of baking soda sprinkled on the floor of the dishwasher and run a short hot cycle. This removes remaining odors and leaves the inside fresh.
Run a full hot cycle with an empty dishwasher to flush everything out and restore fresh airflow inside the unit.
Check the Drain Hose and Air Gap
Look behind the dishwasher and check that the drain hose is looped up high before it connects to the disposal or drain. A hose that sits too low allows dirty water to flow back in. If the air gap on the counter top is blocked remove the cap and clean it out. These are simple checks that can make a big difference.
Plumbing Fixes That Work
A proper trap seal is key because it blocks sewer gas from rising into the dishwasher. If the drain hose sits too low or lacks a high loop dirty water can flow back and cause odor.
Correct drain hose routing keeps wastewater moving one way and helps stop the dishwasher from smelling like sewage.
Call a professional if the dishwasher stinks even after cleaning and basic checks. Blue Sea Plumbing starts with a full drain inspection to find hidden buildup or blockages. Our team checks venting and trap connections to make sure sewer gas stays out of your kitchen.
If the smell is also coming from other drains in the home such as the sink or shower it could point to a wider drainage issue. You can read more in our post on how to tell if you have a water leak underground to understand whether a bigger plumbing problem may be involved.
FAQs
Can a dishwasher smell like sewage without a clog?
Yes. Poor venting or a dry P-trap can let sewer gas escape even when water drains well. If the water drains properly but the smell remains the issue is likely with the trap or the vent pipe rather than a blockage. A plumber can check both without major disruption to your kitchen.
Is a stinky dishwasher dangerous?
Yes. Strong sewer odors may expose your home to harmful gases including hydrogen sulfide. These gases can cause headaches, dizziness, and nausea. If the smell is strong or spreads to other rooms open windows, ventilate the space, and call a plumber promptly. Do not ignore a persistent sewage smell coming from any drain or appliance.
How do I stop my dishwasher from smelling like sewage?
Start by cleaning the filter, spray arms, and running a hot cycle with white vinegar and baking soda. If the smell comes back after cleaning the cause is likely a plumbing issue such as a dry trap, blocked vent, or sewer line problem. These need a professional fix. Contact Blue Sea Plumbing and we can inspect and fix the issue properly.
How often should I clean my dishwasher to prevent smells?
Cleaning the filter once a month and running a vinegar and baking soda cycle every two to three months is enough for most homes. If your dishwasher is used heavily or you notice smells returning sooner than that it is worth having a plumber check the drain setup to make sure everything is connected correctly.
When should I call a plumber about a dishwasher smell?
Call a plumber if the smell comes back after cleaning, if you notice the smell spreading to other rooms, if other drains in the home also have an odor, or if you see water backing up into the dishwasher during or after a cycle. These are signs the problem is in the plumbing not in the dishwasher itself. Our drain cleaning and sewer repair teams are available to help.
