As in the part where the water comes out. "Chances are, if you haven't cleaned this, you will find black, mildewy grunge," says Donna Smallin Kuper of Unclutter.com and author of Cleaning Plain and Simple. "And you're brushing your teeth with that water. Ewww!"
Clean it: Every couple of months, remove the faucet aerator by twisting it counter-clockwise, then soak it in vinegar for at least 15 minutes, Smallin says. (The aerator is actually an assembly made up of a few pieces, including a screen, so take note of how they go back together.) Gently brush all parts with a toothbrush to remove any remaining residue, then screw it back on.
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Handles and Switches
Think refrigerator door handles, light switches, and, of course, the toilet flush handle. "They're easily overlooked in cleaning because they're small, and most people focus on the big things, like floors and countertops," says Debra Johnson, a training specialist at Merry Maids. "Yet everyone touches them, so they have the most opportunity for germs."
Clean it: Use a microfiber cloth dampened with your favorite cleaning product to wipe down handles and switches during your normal cleaning routine.
Above Your Kitchen Cabinets
That no-man's land between cabinets and ceiling is a case of out of sight, out of mind. "We find years' worth of dust, rodent nests and droppings, long-forgotten food, and dead plants," says Derek Christian, owner of My Maid Service and coauthor of The House Cleaning Technician's Manual. "Very few people ever clean this area."
Clean it: Break out the stepladder and your vacuum's hose attachment (or a wet/dry vac). A small hand broom and dustpan will do the trick, too. The space will likely not accumulate enough dust to warrant a cleaning every week, but once a month or so will do the trick. Do this task first so any stray dust lands on surfaces you have yet to clean.
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Any standing water that lingers after a shower or bath breeds mold, fungi, and staph bacteria, says Jackie Harmon, owner of Healthy Clean green cleaning company. "Whirlpool tubs are the worst because water gets trapped in the pipes, so dirt buildup and possibly mold is spouted out during use."
Clean it: Your tub or shower surface should be dried off after each use to reduce bacteria growth. Disinfect regularly, too -- up to three times weekly for tubs used daily by multiple family members. To do so, Harmon recommends filling a spray bottle with a product that contains at least 3 percent hydrogen peroxide, and keeping that near the tub. Lightly mist a dry tub, and you're done. "No need to wipe it up because hydrogen peroxide evaporates quickly," Harmon says. For whirlpool tubs, cycle disinfectant through the pipes monthly according to manufacturer's directions.
Inside the Refrigerator
Sticky takeout containers and long-forgotten leftovers mingle in an awkward space accessed by multiple hands daily. This means refrigerators are destined not only to be dirty, but to land last on the must-clean list -- a serious grime-promoting combo, says Merry Maids' Johnson. Ditto for microwaves.
Clean it: Avoid using chemical cleaners here, Johnson says. Instead, fill your sink with hot water and dishwashing liquid. Remove items from one refrigerator shelf, then remove the shelf itself. Wash it in the sink, wipe it dry with a microfiber cloth, then re-place in the fridge. Repeat for the remaining shelves.
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Your Kitchen Sink
Thanks to all those food particles mingling in a moist environment, the kitchen sink is actually dirtier than your toilet post-flush, according to Charles P. Gerba, a University of Arizona professor and microbiologist known as Dr. Germ.
Clean it: Wash the sink with soap and water daily, and disinfect it with kitchen cleaner once or twice a week.
The Walls Around Your Toilet
"You think you know it's bad, but you have no idea," says Christian of My Maid Service. "I have one of those superpowerful black lights that you see on the CSI shows. See what it reveals and it'll make you want to tear out your drywall and start over."
Clean it: The best cleaners for the walls around the toilets contain enzymes to break down the organic material, Christian says. Spray the walls and let sit for at least a few minutes so the enzymes can do their work. Then wipe down with a damp towel.
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Hands in all states of cleanliness handle it often. Yet it's rarely wiped clean, even after a sick day spent channel-flipping. "The TV remote is one of the germiest surfaces in your home," says Harmon of Healthy Clean.
Clean it: Use a disinfectant wipe to clean remotes often. To get in between the buttons, try a cotton swab dipped in rubbing alcohol.
Under, Alongside, and Behind Your Stove
"Think of all the times you've spilled something between the stove and the counter and not cleaned it up," says Christian of My Maid Service. "Add the ambient heat from the stove to the mix, and you have the perfect place for germs to thrive."
Clean it: You'll have to pull the stove away from the wall. Make this easier and protect your flooring with furniture sliders under the feet of the stove. (A bath mat with the carpet side down works, too.) If you have a gas stove with a flexible hose, pull until the hose is almost -- but not fully -- extended. (If your gas stove does not have a flexible hose, you'll need a pro's help.) Once the stove is pulled out, scrape off buildup with a plastic putty knife, Christian says, then spray the sides of the oven with oven cleaner. Use a good all-purpose cleaner on the adjacent cabinets and floor.
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Inside Your Toothbrush Cup
Not only are they hard to clean, they're usually positioned next to the toilet, which sprays small amounts of fecal debris when flushed. This offender is a simple fix: Keep toothbrushes in a moveable, easy-to-clean cup.
Clean it: Soak the cup in warm water mixed with a little bleach for a half hour. Rinse, then soak in clean water for another 30 minutes to remove the bleach residue. Better yet, use a cup you can toss in the dishwasher instead.