The inside of your kitchen faucet “is the perfect setup for mold to grow,” said Patricia Jackson, the president of the Association for Professionals in Infection Control and Epidemiology. “People will probably be surprised — if they take those aerators off the faucet — at the junk they’ll see in there.” Unscrew the aerator, the small screened part at the end of your faucet, she said. Then, with “good old dish soap and water,” use a small toothbrush to scrub the screen and the inside of your faucet, where mold is likely to build up, she said. While most people exposed to waterborne germs won’t get sick, some groups are more vulnerable, she said, including those over 50 and people with underlying illnesses such as diabetes.