1. Your kitchen sink

“Kitchen sinks are dirtier than most bathrooms,” says Kelly Reynolds, PhD, an environmental microbiologist at the University of Arizona. There are typically more than 500,000 bacteria per square inch in the drain. In fact, in a recent study, half of the top 10 germiest spots in the home were (gulp!) in the kitchen. That sponge you use to clean the counter? Crawling with bacteria, as are the sink’s basin and faucet handles.

Reduce the risk: “Clean your kitchen counters and sink with an antibacterial product after preparing or rinsing food, especially raw fruits and vegetables, which carry lots of potential pathogens like salmonella, campylobacter, and E. coli,” says Philip Tierno, PhD, author of The Secret Life of Germs and director of clinical microbiology at New York University Medical Center. Sanitize sponges by running them through the dishwasher’s drying cycle. “That killed 99.9 percent of the bacteria on the sponges we used in a recent study—and we’d gotten them really good and contaminated first,” says Cheryl Mudd, a microbiologist with the Agricultural Research Service’s Food Safety Laboratory. As for the sink, clean it twice a week with a solution of one tablespoon of chlorine bleach and one quart of water. Scrub the basin, then pour the solution down the drain.