WE ALL know how important it is to wash our hands and we mastered toilet training many, many years ago.

But there is one loo rule that not everyone obeys … and in not doing so you could be exposing yourself to millions of nasty germs.

Not putting the seat down when you flush to toilet sends germs flying all over your bathroom, experts warned.

And one of the grim places they land is on your toothbrush - which ends up in your mouth.

It’s called “the aerosol effect”, Realtor.com revealed.

“You get a good spray out of the toilet area,” Charles P. Gerba, a professor of microbiology at the University of Arizona told the American website.

“When droplets come out of the toilet, it looks like the Fourth of July.”

The most common types of bacteria found in the bathroom are nasty bugs like E.coli, streptococcus and salmonella, which can trigger nasty bouts of food poisoning.

The average person flushes the toilet five to six times each day, adding up to nearly 2,000 flushes per year.

So each time you flush, “an aerosol is created due to the rush of water into the bowl,” Jason Tetro, a visiting scientist at the University of Guelph and author of The Germ Files: The Surprising Way Microbes Can Improve Health and Life (and How to Protect Yourself From the Bad Ones), added.

“When this happens, any microbes deposited into said toilet may be sent into the surrounding environment.”

Bacteria can fly 10 inches up into the air, Leeds Teaching Hospital revealed in a previous study.

But, as well as shutting the loo seat, there are other ways you can reduce the risk of toilet germs hitting you - and your toiletries.

Professor Gerba suggested moving your toothbrush at least 3ft away from the bowl.

It’s also worth using a ‘drop-in’ toilet cleaner to make sure the loo is kept as clean and fresh as possible.

Meanwhile, experts believe we would be better off ditching toilet paper completely.

While countries such as Japan, Italy and Greece use bidets as a way to clean their behinds, countries such as Britain, the US and Australia mainly rely on a bit of trusty loo roll to do the job.

But, doctors say wiping could be leaving faeces behind and excessively wiping could cause health problems such as anal fissures and urinary tract infections.

Rose George, author of The Big Necessity: The Unmentionable World of Human Waste and Why It Matters, told Tonic why using toilet paper doesn’t remove poo properly.

She said: “I find it rather baffling that millions of people are walking around with dirty anuses while thinking they are clean.

“Toilet paper moves s***, but it doesn’t remove it.”