If you make good use out of your kitchen, there are probably a few items you regularly use that are past their prime. Some may be easy to spot based on scratches, scuffs, and funky smells, while others may more sneakily breed ickiness. To help you eliminate the guesswork, we asked food safety expert Trevor Craig, corporate director of technical training and consulting at Microbac Laboratories, which kitchen items you need to replace more often, including the when and why. Keep reading for all of the dirty details.

The common kitchen items and tools you should replace *right now*, according to a food safety expert

1. Sponges

When to replace: Once a week

ICYMI, your kitchen sink is among the dirtiest places in the kitchenand your entire home. In fact, in a research project from the USDA’s Food Safety and Inspection Service, experts found the most contaminated kitchen surface post-meal prep was the kitchen sink—followed by the fruit washed in the sink. Ick.

As such, it’s no surprise that porous sponges—which not only sop up oil, grease, and food bits but also transfer them—are a literal breeding ground for bacteria. A 2017 study from Scientific Reports found 362 different species living in used kitchen sponges¹—with as many as 54 billion bacteria per cubic centimeter. Ick. “I recommend replacing sponges once every week or so [since] they can be difficult to clean and quickly accumulate food particles and general debris,” Craig says.

2. Cleaning brushes

When to replace: Every few months

Cleaning brushes also top Craig’s list of kitchen items to replace more often than you probably do. Similar to sponges, they “can get dirty, accumulate bacteria, and spread it around,” he shares. That said, they’ll typically last longer than sponges due to their more resilient composition; research shows that they tend to have lower bacteria levels than sponges².

A good rule of thumb is to replace your kitchen cleaning brushes every few months. “If you clean your brush right away, most of the food comes off and you don’t have to scrub much,” Craig explains. “If you are heavily using them, replace them when they start to show some wear and tear, which could be every month in some situations.”

3. Washcloths and dishtowels

When to replace (for cleaning): Daily

Whether you use washcloths to clean kitchen surfaces, dry your hands off, or stand in as a napkin (or all of the above), Craig says that your best bet is to wash any kitchen washcloths or dishtowels  daily. After all, you wouldn’t keep a dirty paper towel lingering post-use, right? “Washcloths are easy to replace because you can just throw them in the laundry and reuse them,” he says.

4. Cutting boards

When to replace: Every six months

Shifting from kitchen cleaning staples to food prep gear, cutting boards are another item you’re likely keeping on hand for longer than you should. “When they get very scratched, they can leach dangerous chemicals and become areas where bacteria can get into and grow,” Craig warns. Generally speaking, he suggests replacing your cutting boards about every six months—or sooner if they’re significantly scuffed up, filmy to the touch, or harboring some stink.

However, this timeline may vary based on the material of the cutting board. “Some types of wooden cutting boards have some antimicrobial properties so they can be kept for longer,” Craig explains. “For example, wooden cutting boards that are not pressed wood have shown an ability to kill dangerous bacteria when treated correctly.” (Here’s how to oil and treat a cutting board to help it last longer.)

5. Kitchen knives

When to replace: Every six months (or longer, depending on quality)

Knives with handles may be among the more surprising items making this list of kitchen items worth replacing more often. You’ll know that a knife is past its prime when the handle shows cracks and/or the settings loosen up. “The cracks in the handles themselves can be a place where juices and food particles can get into and harbor dangerous bacteria,” Craig warns. “These items tend to be some of the least cleaned items in kitchens to keep them sharp, which creates a dangerous situation for food-borne illness in your kitchen.”

Do yourself a favor and keep a watchful eye on the quality of your cutting knives. Craig says you may need to replace them around every six months, though the timeline will vary based on their quality and how often you use them.

6. Plastic storage containers

When to replace: Varies

Is it just me, or do most of us hold onto plastic storage containers forever? All too often, they’ll show discoloration and retain funky smells… but those aren’t the only reasons why they should be tossed more frequently. “You should replace plastic food storage containers once they get cloudy, scratched, or warped,” Craig advises. “Once this happens, bacteria can grow, and in some situations, the container won’t provide the proper type of seal to keep your food fresh and safe.”

Timelines for usage will vary based on the type of plastic container you have and how well you maintain it. For instance, the kinds used for takeout and delivery food should typically be limited to single use. Craig says they’re generally not designed for washing, heating, or reusing, so you’re better off recycling them straight away. In addition, he cautions that some types of plastic food containers aren’t microwave- or dishwasher-safe. “Putting them in these conditions can break them down and cause them to be unsafe,” he shares, so be sure to follow the manufacturer’s instructions and guidelines.

In many cases, opting for glass storage containers will be “cleaner” from a food safety perspective, as well as more eco-friendly. (Not to mention oh-so satisfying and chic, if you ask me.) Craig adds that glass containers are a great alternative since they’re more resistant to casual wear and tear. “Just don’t drop them or chip them because they don’t have the bounce of a plastic container,” he says.

—reviewed by Jennifer Gilbert, MD, MPH