Do you know what lives in your knickers? If you did, you'd put them on a boil wash

Do you know how many bacteria live in your dirty underwear? If you did, you'd probably be so grossed out that you'd toss them after one use. Or wash them in boiling water. And definitely not wash them in the same cycle as your tea towels or face flannels.

With Stella McCartney's recent statement that she doesn't wash her bras making waves across the media, the attention now turns to to our most intimate wear: our underwear bottoms. And – no surprises here, really – it turns out that our pants are breeding grounds for loads of bacteria (thanks, faecal matter). The answer seems to be obvious: wash your underwear in hot water. 

However, in a recent article for the Sun, an immunologist from the University of Sussex is quoted as saying that even 60ºC water will not kill all the bacteria that lives in your knickers. Besides, what do you do if your underwear is made from silk, and cannot be washed in hot water? 

The answer is to disinfect your washing machine, frequently. An article by The Laundry Alternative explains that the problem isn't really the presence of bacteria on our clothes – they've been there as long as we've worn clothes. It's the fact that people nowadays use low-temperature cycles as standard, allowing bacteria to accumulate inside the washing machine and transfer onto all subsequent wash loads. 

According to an American study, 60 per cent of washing machines were found to contain e-coli and salmonella, as well as other common pathogens. Which, of course, will transfer on to anything else that goes in there.

This seemingly scary problem has a simple solution, though: run your washing machine on the hottest cycle (90ºC and above) at least once a week, without any laundry in it, using bleach or powder detergent. This will not stop all bacteria entering the washing machine (nothing will), but it will prevent them from reaching numbers that could make you sick.  

Get more advice on how to clean a washing machine in our guide.