Before you start cutting that meat you’ve been storing in the fridge on the cutting board, make sure the surface is clean first. Cutting boards should be cleaned in hot soapy water, especially after being used for raw food items, and it is recommended to have a separate cutting board for food that will be cooked and food that won’t. It’s one major kitchen item that could secretly be home to illness-causing germs.

The dishcloth that you use to clean your counter and hand-dry dishes often comes in contact with food residues that can build up and create a home for bacteria and other microorganisms to grow. The Center for Science in the Public Interest recommends having a fresh stack on hand to start with a new one each day that you throw into the hamper every night. 

Inside your refrigerator, food that has been stored too long or incorrectly is at risk of two types of bacteria: pathogenic bacteria, the kind that causes foodborne illness, and spoilage bacteria, the kind that can lead to unpleasant odors, tastes and textures. Discard any foods that have gone bad and wipe down the shelves with disinfectant. Here is how to tell if many popular foods have gone bad. 

The 2011 NSF International Household Germ Study found that refrigerator handles were one of the places in the home that carried not only coliform, yeast and mold, but also staph bacteria. The fridge handle came in second only to the sponge for staph, with it being present in 14% of homes. Take a disinfectant wipe to the handle regularly — here is how to use disinfectant wipe properly.  

Salt and pepper shakers can accumulate bacteria as many different people touch them, oftentimes without cleaning their hands first — a bad cooking habit that people should stop now. A study by the University of Virginia found that salt and pepper shakers were the top hotbed for the presence of rhinovirus, more than remotes and faucets. Remember to wash and disinfect shakers regularly when cleaning the house.

It is a misconception that because the sink is an area where things get cleaned, that it is clean. In reality, it can be a breeding ground for the bacteria from the dirty dishes and raw food being rinsed. After you eat your favorite meal and wash the dishes, remember to deep clean the whole sink, including the faucet. 

A sponge is, well, a sponge for foodborne pathogens, yeast and mold, making it one of the biggest hidden sources of bacteria in your home. According to the USDA, sponges should be cleaned by putting them in the microwave for one minute or in the dishwasher on a dry cycle.

Think about it: a lot of people are touching light switches with their bare hands several times a day. In the NSF study, light switches, especially in bathrooms, were found to have coliform, yeast and mold. Disinfect light switches often with spray or wipes, because turning off the lights is one way to save money while you’re at home. 

Sensing a theme? The more hands that come in contact with something, the more bacteria will accumulate. The NSF study found yeast, mold and coliform data present on TV remotes, and even staph in some homes. A remote can be busy as the family watches their favorite heartwarming TV shows, so the Centers for Disease Control and Prevention says to consider the use of wipeable covers for electronics like tablets and remote controls. If no manufacturer guidance is available for cleaning, try alcohol-based wipes or sprays containing at least 70% alcohol.

Anything with the word garbage in it is bound to be dirty. People dispose of food residue, grease and other things down the disposal, and according to the NSF study, the second-highest concentration of microorganisms was found in the kitchen sink. A disposal should be cleaned at least once a month by pouring a solution of 1 tablespoon household bleach and 1 quart of water down the drain. Here’s the average shelf life of the most common cleaning supplies like bleach.

Canned foods can have a long shelf life, making them popular items to stock up on. But the tool we use to open them, a can opener, is one of those items everyone should clean but doesn’t. The NSF found traces of salmonella, E. coli, yeast and mold on the can openers tested. A can opener should be cleaned after each use in the dishwasher or by hand in hot soapy water, with attention on removing any residue. Then, wipe with a bleach solution to disinfect.  

If every member of your family drags their hands along the stair railings every time they go up or down the stairs, then you’re going to want to wipe them off with disinfecting wipes regularly — and more often if a family member is sick. First, it’s important to know that dusting the railing is not cleaning it. For a moderately trafficked wood rail, dusting should be followed by 1 cup of olive oil and half a cup of lemon juice to clean. For a heavy-duty job, mix 2 cups of water and 1 cup of white vinegar into a bottle and spray directly onto the railings. Allow the mixture to sit for a minute and clean with a soft cloth.

A knife block may be good for kitchen organization and the knives you’re storing may be clean, but those deep recesses might still be harboring mold, yeast and bacteria, especially if the knives are still a little damp when you’re putting them away. To clean, remove all the knives, shake out any crumbs and debris, and hand-wash the knife block in hot soapy water. Use a small brush to get in the knife slots and then rinse it with cold water. 

Over time, your mattress can accumulate a lot more dead skin cells and dust mites than you care to imagine. But it can also accumulate yeast, mold, E.coli and staph bacteria deeper inside the mattress. That is not to say you need to replace your mattress every six months, because a mattress has a lifespan of around eight years. But to clean it, take off the sheets, vacuum and then let baking soda sit for an hour before vacuuming it back up to remove stains and odors. You can also spot-treat using heavy-duty cleaning supplies so you can sleep better. 

Your kitchen counter may look clean while you’re cooking your easy weeknight dinners, but it could be harboring dangerous bacteria. When the NSF swabbed for coliform bacteria, which includes salmonella and E. coli, it was found on 32% of countertops. To clean, first remove any food residue or liquid that is on the counter and then wipe it with an antibacterial cleaner. Then it’s time to disinfect. Yes, there's a difference between cleaning and disinfecting. You can save money on cleaning supplies by making your own wipes with bleach or alcohol.

The bathroom area where the NSF study found the most coliform may surprise you. This bacteria was found on 27% of toothbrush holders. In 14% of households tested, staph was also found. That was worse than the toilet seat. The holder should be cleaned at least once a week. If the holder is dishwasher safe, just pop it in with hot water and detergent after a pre-soak to remove gunk. No dishwasher? A good 10-minute hot water soak and scrub with dishwashing liquid will do. Just dry thoroughly.

Clean machinery is one of the secrets behind making good coffee at home, but most people don’t clean their home coffee makers as often as they should, which is after every use with soap and water. The water reservoir in your coffee pot is damp and dark, making it the perfect breeding ground for bacteria, and the coffee maker was one of the germiest items found by NSF with mold, yeast, coliforms and E. coli. Clean it regularly by pouring equal parts water and white vinegar into the reservoir, then turning on the coffee maker and running it like you would if you were making coffee. Give it a rinse and you’re good to go.

Even with can liners and trash bags, garbage cans are going to get dirty with grime and many forms of bacteria. A 2007 study by the Hygiene Council found that on average, there are over 411 million bacteria per square inch in a garbage pail. To clean your garbage can, empty all the remaining food and trash, pour an all-purpose cleaner on a paper towel and wipe down the can on the inside and out. Then rinse it with water and let it air dry. 

Toys are used for fun activities both indoors and out for some of the most popular pets. That means they’re also touched by many bare hands, put in pets’ mouths and on the ground. They were found to have yeast, mold and staph bacteria. If the toys are plastic, wash them with soap and water. Toys that are plush and fabric can be cleaned in the washing machine. 

Respondents in the NSF study guessed that the bathroom doorknob was one of the germiest places in the home. But in fact, stove knobs turned out to be much dirtier. Nearly 30% of homes had yeast and mold data on the stove knobs, making them the seventh dirtiest place in the home. To clean a stove properly, make sure to remove the control knobs to wash them.

Makeup brushes are among the items you need to stop sharing with others right now. Very quickly, brushes can get filled with product residue, dirt and oil, making them a breeding ground for bacteria and E.coli that can cause fungal or staph infections. The American Academy of Dermatology recommends washing your makeup brushes every seven to 10 days with warm water and clarifying shampoo.

Many people think about cleaning the inside of their microwaves, but not the outside. Well, in the NSF study, microwave handles came out as the fourth-dirtiest spot in the home with not only coliform, yeast and mold, but also positive traces of staph. Clean the handle with a disinfectant spray or wipe before you warm up those leftovers.

Although this is a place for plenty of indoor kids activities, it can also be full of dirt, germs and bacteria. A carpet can collect a variety of particles, such as dust mites, pet dander, mold spores, dirt and dust, which then attract bacteria, germs and bugs. To get rid of all of the visible dirt on your carpet, vacuum regularly and get it professionally cleaned every 12 to 18 months to get out dirt that is embedded in the carpet.   

A pet’s bowl was one of the few household items in the NSF study that had positive E.coli, coliform, staph, yeast and mold. Wash food bowls after every meal with hot soapy water. 

One of the biggest misconceptions of participating homes in the NFH study was that the bathroom was the dirtiest room in the house. In reality, many of the warm, moist kitchen items listed above proved that theory wrong. In fact, after addressing the dirtiest bathroom item above, the toothbrush holder, not much more came close in coliform data — bathroom faucet handles were at 9%, followed by the toilet seat, bathroom doorknob and bathroom light switch all at 5%. But that doesn’t mean those items don’t need to be disinfected. Here is how to properly deep clean your home.

More  From The Active Times:

How to Deep Clean Things In Your House You Might Forget

Hand Sanitizer, Disinfectant Wipes and More: What’s the Shelf Life of Cleaning Supplies?

How to Save Money on Cleaning Supplies

CDC-Approved Cleaning Products: Keep Your Home Sanitized From Carpet to Countertop

Deep Cleaning House Tips From The Pros