Your Coffee Maker Is Disgusting Clean your kitchen pretty often? It's not as tidy as you think; especially if you've never washed out the inside of your coffee maker. According to a new study, the device that gives life to your mornings could be one of the dirtiest things on the counter, potentially leading to allergic reactions or infections. The National Sanitation Foundation International found that more than half of the water reservoirs they tested were covered in mold and yeast. Coliform bacteria were also detected. Depending on the machine you own, Delish points out that vinegar could help with the disinfecting. Or there's a cleaning solution you can pick up. On the outside, give a pass with Clorox wipes.