Why Does My Dishwasher Smell Like Sewage?

Picture this: you open your dishwasher to load in some dirty dishes and are hit with a wave of unbearable stench. What could be causing this? And more importantly, how can you get rid of it?

Unpleasant dishwasher smells are pretty common and can result from a range of factors, including rotting food, standing water, and even the wrong dish detergent. Our guide will help you pinpoint the reason and ensure you can rid your dishwasher of unpleasant odors once and for all. Read on to find out what to do!

What Causes Bad Smells?

In almost all cases, a smelly dishwasher is due to bacteria. Bacteria thrive in warm, moist environments, so a dishwasher is perfect for them. Bacteria can feed on food debris and even detergent. And as the bacteria increase, so do the unpleasant odors! The gasses produced by the rotting food can often smell so bad that people compare it to sewage—not something you want in the appliance that cleans your dishes!

Rotting Food

Food particles are often to blame for bad smells in your dishwasher. A dishwasher has plenty of small nooks and crannies where food can become trapped, such as the filter and the spray arms. When the food is left for a while, bacteria begin to feed on it while it rots, leading to foul smells. 

Standing Water

Another common culprit behind a smelly dishwasher is stagnant water. If your dishwasher isn’t draining properly, water will collect at the bottom, creating the perfect breeding ground for bacteria and mildew. If left for a while, the smell can get extremely strong—particularly if you’ve not used your dishwasher for a while. Pooled water is the obvious sign that this is the cause of your smell issues. 

Detergent Buildup

Overuse of detergent or using the wrong detergent brand can also lead to unpleasant smells. Over time, a residue can build up, creating a breeding ground for certain types of bacteria or mildew that can feed on it. This can lead to a slimy coating on the interior of your dishwasher that gives off a strong, unpleasant smell. 

Water Siphoning

The phenomenon of water siphoning can occur when your dishwasher drainage hose isn’t installed properly. This means that water from your kitchen sink or garbage disposal can flow into the dishwasher and then sit in the bottom, creating an ideal breeding ground for odor-causing bacteria. 

How To Get Rid of Bad Smells

It’s all very well to know what’s causing your dishwasher to smell like sewage, but how can you get rid of the horrible odor? Although the solution will differ depending on the exact cause of the odor, the following methods will work to get rid of almost all nasty smells. 

Clean the Filter

The first step is to thoroughly clean your dishwasher filter, which traps all of the food debris that’s removed during washing. While the process differs slightly depending on the make and model of your dishwasher, in general, you need to follow these steps:

• Remove the lower rack of your dishwasher. 
• Remove the filter cover (if you have one) and lift out the filter. Usually, they unscrew counterclockwise. 
• Remove all food debris from the filter and rinse it thoroughly under running water. 
• If you find any stubborn debris, use a brush to scrub it away. 
• Use a cloth to wipe out any debris in the filter housing. 
• Replace the filter and filter cover. 

Drain the Water

If the smell in your dishwasher is coming from standing water, then the water needs to be drained. Usually, if you clean out the filter, the water will drain in the next dishwasher cycle, but you also may need to check for blockages in the drainage hose. Here’s what to do:

• Move your dishwasher away from the wall to gain access to the drainage hose. 
• Check to ensure the drainage hose isn’t kinked or pinched, preventing proper drainage. 
• With an old towel on hand to catch runoff, disconnect both ends of the drainage hose and check for blockages. 
• Clear out any blockages with a length of wire or a long brush. 
• Reconnect the drainage hose and run a test cycle to ensure the issue of the standing water is fixed. 

Check for Siphoning

If you suspect that water siphoning may be behind the sewage smell in your dishwasher, you’ll need to ensure that your drain hose is installed correctly. 

Check the drainage hose installation. To prevent siphoning, the hose should either utilize a high loop or an air gap system.

• A functioning high loop requires part of the drainage hose to go upwards in a loop before it reconnects to the drain. If this is the system your dishwasher uses, ensure that the loop is high enough and use something to hold the loop in place if necessary. 
• An air gap is a small, cylindrical device that sits on your countertop and ensures there’s a gap between the dishwasher’s drain line and the dirty water. Check to ensure the air gap isn’t damaged. You may need a plumber to help you install an air gap correctly. 

Deep Clean

Once you’ve fixed the underlying issue causing the sewage smell, your dishwasher may still have some lingering unpleasant odors. A deep clean can get rid of any last remnants of odor-causing bacteria, ensuring your dishwasher smells fresh and clean. 

• If you haven’t already done this, clean the filter as outlined above. 
• Thoroughly wipe down the interior walls of the dishwasher, using a soft cloth and mild detergent. 
• Clean the dishwasher seals thoroughly – these can be a breeding ground for mildew and bacteria. 
• Remove the spray arms and soak them in a solution of water with a small amount of bleach before replacing them. 
• Run an empty cycle with a bowl of white vinegar placed on the top rack. This will help to eliminate odors. 

Odor Prevention

To stop the smell from coming back:

• Clean the filter regularly—at least once every two months. 
• Make sure you’re using the detergent recommended by your dishwasher brand. 
• Once every three months or so, run a deodorizing cycle with a bowl of white vinegar. 
• If you ever notice standing water, resolve the drainage issue immediately. 
• Regularly check and clean the door seals.