You don't need to wash your bras as often as you might think.

Image: iStock.

In most cases, laundry advice revolves around the words “more often”.

Clean your sheets more often. Chuck your pillow cases in the washing machine more often. Wash your scarves more often (oh, what’s that? You don’t wash your scarves ever? Naughty, naughty). If you don’t, a lethal combination of bacteria, microscopic insects and sweat build-up will start to bury into the surface of your skin, gnawing away until there’s nothing left. Or so the tale usually goes.

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So it’s kind of nice, just once, to hear that it’s perfectly acceptable — advisable, even — to wash something less often. Apparently, this ‘something’ is your bra. (Post continues after gallery.)

A pair of cleaning experts have told Cosmopolitan magazine that over-washing bras can actually damage their structure and elasticity, thereby compromising the boob support it offers. Which would be kind of counter-productive.

“Once a bra loses its shape, the fit is compromised,” says Carolyn Forte, director of the GHI Cleaning Lab.

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As for how often you need to chuck your bra in the laundry basket, ignore anyone who tells you it’s necessary after every single wear (sorry, Mum, but you’re not right about that one).

"Every few wears should be sufficient, but it does depend on your activity level," says Lexie Sachs, product analyst in the Textiles Lab at the Good Housekeeping Institute.

Keep in mind that you don't always wear the same bra on consecutive days, so it could be 10 days to a couple of weeks before you get into your third or fourth wear.

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"For instance, if you're outside on a humid day and end up sweating a lot, you'll want to wash your bra sooner. On the other hand, if you throw a bra on for a couple hours, that might not count as a 'wear.' Washing gets rid of the oils and germs that accumulate, so the more oil you're producing, the more frequently you'll need to launder your bra," Sachs adds. (Post continues after gallery.)

In other words, you probably want to wash your sports bra more often than that sexy balconette you bring out for date nights, and wash bras more regularly in summer than winter. But you'd probably already figured that out. When in doubt, abide by the sniff test (and be honest with yourself).

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Sachs and Forte also recommend you aim to rotate through a few bras in a week, and take them off at night, to avoid stressing the elastic. But it's no biggie if you don't manage to do this every time, because it's not always possible.

Of course, it goes without saying that your matching undies do need washing after every wear. There's no way you can get away with that one.

How often do you wash your bras?