house cleaning

What's the dirtiest place in your house?

In 2011, NSF International, swabbed a "sticky note"-sized area of many commonly found items from the homes and cars of 22 volunteer families. Then, they examined these samples for Coliform bacteria (which includes Salmonella and E. coli) to identify the most germ-infested items we come in contact with daily. What they learned was not what most of us would expect.

And why is this so important? Because 80% of all food-related illnesses originate from inside the home!

Can you guess the top 5 dirtiest items in most homes?

Below is a scrambled list of 5 items that research suggests are the filthiest things in the average home and 5 that are commonly among the cleanest.

Instructions: Sort (click, drag and drop) each item, arranging what you believe to be the 5 dirtiest on the left and the 5 cleanest on the right. Then, compare your selection to what the research found:

Drop 5 Dirtiest Items Here
Drop 5 Cleaner Items Here

:: Refrigerator handle

:: Dish sponge/rag

:: Bathroom light switch

:: Toothbrush holder

:: Coffee reservoir1

:: Money

:: Toilet handle

:: Kitchen sink

:: Pet bowl

:: Keyboard

1. Coffee reservoir is the top of a coffee maker where you add water and grounds.

Click to see the correct order of items and cleaning recommendations

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Feedback for the Dirtiest Items in Your HomeAdd Comment
February 6, 2018
Very interesting post. They've even now determined the germiest places in airplanes. The most germy is the flush button on the toilet -- which is about 10 times germier than the second germiest surface, seat-back tray tables! But far filthier than airplanes are the airports! The self-service ticketing kiosks at the check-in counter is more than 20 times as germy as those on-plane tray tables!!
Charlotte at Florida Health
February 7, 2018
Great information, Elsie. Thank you for sharing that. I did a quick search and found this on It may be what you are referring to. If my calculations are correct, those aiport kiosks are 70 times as dirty as the kitchen counter in a typical home!

But, it seems like every study returns different results. In 2015 they tested the cleanliness of airplanes and determined the dirtiest surfaces to be 1) tray tables, 2) overhead air vents, 3) toilet flush buttons and 4) seat belt buckles. Shockingly, that study found bathroom stall locks inside airports to be extremely clean. (How can that be?!) They were harboring only 1/5 as many germs as the typical home's kitchen counter.

I guess the bottom line is to wash your hands well... and often. And avoid rubbing your eyes or nose.
Charlotte at Florida Health
December 1, 2018
Related to this subject of staying healthy while flying, here is an air travel alert from the LATimes: Why you shouldn't drink tap water, coffee or tea on commercial airplanes.
KP in Miami
August 4, 2017
It is good to know that the germ scientist you mention above still recommends chlorine bleach, alcohol, and hydrogen peroxide as the best sanitizers when cleaning around the house. I read recently that microwaving the kitchen sink sponge, with the intention of sanitizing it, actually makes the problem it worse. Who would have ever guessed that!
Charlotte at Florida Health
August 5, 2017
Thanks for your comment, KP. Perhaps this is the article you saw, about the microwave not being effective at killing germs:
It goes on to say that washing that sponge in the laundry machine or dishwasher, soaking it in vinegar or even cooking it on the stove are also ineffective. Their suggestion is to discard your old kitchen sink sponge each week or so and start fresh but, personally, i sure prefer using a dish scrub brush with plastic bristles.
April 14, 2017
I wonder if they've done a similar study of hotel rooms?
Charlotte at Florida Health
April 15, 2017
Good question! The University of Houston did an often cited study on just that topic -- with the hopes that it could help hotels better identify and focus on those hotspots. And while most of us judge the cleanliness of a hotel room according to how it looks, they determined that this is not a good way of measuring sanitation.

Turns out, some of the dirtiest items in hotel rooms are the cleaning related: maid's cart, mops and sponges... which means the germs constantly get transferred from room to room. Also near the top of their germiest items list is bathroom sinks, toilets, bedside lamp switch and TV remotes. Most surprisingly, bathroom door handles averaged out to be one of the least germ-contaminated hotel room items.

The filthiest places in offices tend to be 1) break room sink faucet handles, 2) microwave door handles, 3) keyboards, and 4) refrigerator door handles. The cleanest tends to be, once again, the toilet seat!
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