Many common items in your home can harbor—even actively grow—bacteria, mold, mildew, dust mites, odors, and other yucky stuff. Routine washing is your best defense. But, how frequently you should wash often depends on a combination of things:

• On a scale of damp to sopping, how wet does it typically get?
• Does it come into routine contact with body fluids?
• Is it allowed to air-dry thoroughly between uses?
• And, does is get regular exposure to fresh air and bright sunlight?

Use the following wash guide as a starting point with the understanding that robust daily and weekly maintenance routines typically enable you to get away with less frequent deep cleaning.

BATHROOM

SHOWER CURTAIN/LINER The guideline here is to wash it before you see any signs of mold or mildew growth. For most households, that translates into about once a week or every two weeks if you’re in a habit of running the bathroom fan when bathing and pulling the liner out of the bathtub, so it can air dry each day after the last shower.

BATH TOWELS Hanging up and reusing bath towels is a great way to save on energy, water, and detergent use. The flip-side is that bath towels have all the best conditions—damp, dark, plush, frequent body contact—for growing bacteria. Assuming you always hang up bath towels to dry thoroughly between uses, you should still probably wash every 2-3 times they get used.

HAND TOWELS Washing hands is the undisputed best way to limit the spread of infection. But you can’t assume everyone washes their hands with the same degree of thoroughness, so it’s best to swap and wash hand towels at least every other day or so. Something else to know is that washing—even with hot water and bleach—doesn’t typically kill all germs; towels especially accumulate germs as they age, so replace altogether on occasion, as well.

BATH MAT Once a week or with each load of bath towels should do the trick for keeping your bath mat respectably clean. If the mat has a slip-proof rubber backing, frequent washing cause that backing to deteriorate, so keep that in mind the next time you’re picking out a new mat.

BEDROOM

SHEETS When it comes to washing sheets, recommendations from cleaning PROs range from once a week (ideal) to, at most, once every two weeks. A few of the factors that might influence where you fall in that range include: tendencies to perspire or drool when sleeping, wearing/not wearing PJs, bathing before bed, daily bed-making behaviors, allowing pets to sleep with you, and many others.

DUVETS/COMFORTERS First question: is it covered? If yes, wash the cover whenever you wash your sheets, then wash or professionally clean the comforter once a season. If you don’t use a duvet cover, wash the comforter as often as you wash your sheets. Second question: do you use a top sheet? If yes, you can probably push washing a cover once a month.

BLANKETS The wash guideline for blankets depends on use. If used routinely, wash with sheets; if used only on occasion, wash or clean once a month or so.

MATTRESS PAD/COVER While sheets provide a layer of protection here, they still allow human body fluids (such as sweat) and dander to seep through, creating a feeding ground for dust mites. Even if a mattress cover is guaranteed to repel mites, wash mattress pads and covers at least once a month.

BED SKIRT As long as you make a regular habit of moving and/or vacuuming under and around the bed – and no one who sleeps in the bed suffers from dust or related allergies—once a season or even twice a year should suffice for washing or dry-cleaning bed skirts.

PILLOWS Assuming you wash pillow cases and/or protective pillow covers once a week (or every two if that’s your sheet routine), you can likely get away with washing pillows just once a season or every six months. The exceptions would be for people who perspire heavily, drool in their sleep, or suffer from allergies or asthma.

LIVING AREAS

WINDOW TREATMENTS If you make a weekly or bi-monthly habit of vacuuming blinds and window treatments, you can get away with washing or cleaning window treatments only once a season or twice a year.

THROW PILLOWS/BLANKETS Decorative throw pillows often come with removable/washable covers and inserts. As with window treatments, if you vacuum them weekly, you can get away with washing only once a season. The same is true for cozy throw blankets and slip covers.

KITCHEN

SPONGES Synthetic sponges are pretty much germ factories and should be essentially sterilized with each use. Either drop into boiling water or run through a very, very hot dishwasher cycle. Better yet, trade in your sponges for cotton dishrags that you can throw in daily with just about any load of laundry you happen to be running.

DISHTOWELS Especially if you use them to dry dishes, serving platters, and utensils, which won’t benefit from high cooking temps to kill surface germs, be sure to wash dishtowels with each use and also replace on occasion.