Dirty Dishwashers

Most of us love our dishwashers, and the convenience of being able to just toss in our dirty dishes, add some soap, push a button and come back to beautiful, sparkling clean dishes.  And yes, the dishwasher gets our dishes very clean.  But have you ever taken a moment to consider the dishwasher itself?  And have you thought about the nooks and crannies that could be holding bacteria, mold or fungus?  Have you looked up into the top back corners of your dishwasher?  What about that rubber gasket that keeps the water from seeping out? How do things look around your soap dispenser?  Unfortunately, the moist, warm environment of the dishwasher can be a breeding ground for many kinds of fungi and other pathogens that we don’t want our family exposed to.  You can find a lot of information on the internet about what could be growing in your dishwasher, and here are just a few excerpts-

According to the www.NYdailynews.com – “With their moist, warm environment, dishwashers are a “major indoor niche” for harmful fungal pathogens, including black yeast-like fungi that can cause breathing problems in some people, according to Turkish researchers. Black yeasts thrive in hot, moist conditions, and may lurk in the rubber seals of dishwasher doors, researchers noted.  And all that dishwasher soap isn’t doing the trick: it contains salt, which yeasts also thrive on.”

“When you allow dishes to accumulate for a few days, growth of bacteria invariably increases,” says Philip Tierno Jr., Ph.D., director of microbiology and immunology at NYU’s Langone Medical Center and the author of The Secret Life of Germs. “And even if you can’t see it, there is viable foodstuff in the rinse water to feed them.” Plus, the dishwasher’s door gasket may be contaminated with fungus and black yeast. “That outer rim never reaches a temperature high enough to kill everything off.” 


According to a study by Dr. Polona Zalar, as reported in the www.dailymail.co.uk/health, ” ‘We conclude that high temperature, high moisture and alkaline values typically occurring in dishwashers can provide an alternative habitat for species also known to be pathogenic to humans.’ “

As with anything we are blessed with, we must be good stewards.  I used to think that running some vinegar (or bleach) through my dishwasher would sanitize and clean it, making it germ free.  Yes, a run with vinegar is certainly better than nothing, but once I started digging in, I knew that my quick cleaning method just wasn’t doing what I thought it was.  What I thought was spotless and safe was actually a breeding ground for those nasty bacterias, fungi and molds.  Here are some pictures of my super-cleaned and sanitized, 11 year old dishwasher, and my methods for cleaning this appliance.

It’s important that you take your dishwasher apart, clean in detail, and have a routine for preventing the unwanted growths in this warm, humid environment.  I start with removing the silverware holder, and each of the racks.    For the cleaning solution,  you can create a sanitizing solution with a spray bottle (32 oz.) of water, and roughly 3 TBS. of bleach.  This should sanitize at about 200 ppm of chlorine which is deemed to kill bacterias such as E-coli, and fungi such as Black Yeast. Yes, you can use a vinegar solution if you don’t want to use bleach, although it is unlikely that it’s results will be as fast or as reliable.  This vinegar solution should be at least 3 parts vinegar to 1 part water.  Note- make sure that you are covering the floor or any cabinetry surrounding the dishwasher to avoid contact with bleach. And if you are sensitive to smells, wear a mask or use other precautions to avoid inhaling the bleach aroma. 

Once I pull out these parts, I clean each thoroughly by spraying with the solution, scrubbing with a brush (the agitation of the brushing helps to kill the germs), and then allowing them to air dry.


I then move into the dishwasher itself, starting with the parts on the door.  Look in and around the soap dispenser, the vents knobs, and any other grooves or indentions that could harbor food or dirty water.  


From there I venture into the rubber gasket area.  This part is tricky because you want to scrub it well, but without damaging this gasket.  I find that one of those nylon scrubby sponges, along with my sanitizing cleaner, works well.  Make sure to get in the edges, especially near the bottom inside where the door connects, and remove all the built up mold and grime.


Next I work on the “arms” that hold the top rack.  They have a lot of grooves, and I pull them out as far as they will go to be able to get my sponge, rag, or brush in the areas that need cleaning.  


Moving into the interior of the dishwasher, I start by cleaning out the bottom near the drain.  Make sure there are not food particles in the drain.  Turn the spinner around a few times and really get in there where you can see.  Spray the area with your sanitizer, brush lightly around the drain area, and let the solution just sit there while you work on the rest of the interior.  


Here’s where you can tackle that top back of your dishwasher.  I spray the top and back and sides with my spray, wipe down where necessary, and leave the solution to continue sanitizing. 


Once I feel like I have touched every part of my dishwasher, I am ready to put the racks and the silverware holder back in, and run it through a rinse cycle.  This will be enough to spray hot water all over the areas that you have cleaned, and will rinse off the sanitizing spray leaving a sparkling clean, and much safer dishwasher.



Disclaimer:  Although I have received National Food Safety Certification, I am in no way an expert in bacterial or fungal growth.  These are my own methods that work for me and my family, and should not be considered to be professional advice.  

4 thoughts on “Dirty Dishwashers

  1. Wow! Makes me glad I don't have a dishwasher. I've had friends tell me that they don't get sick as often since they quit running their dishwasher. I didn't understand that, but after reading this, I wonder if this is why.

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