Ralph Riley: "Showering removes most pollution"

"It's down to the actual management on site and that's monitored in a general sense by the Health and Safety Work inspectorate, they can come out any time they like and carry out inspections.

What tends to happen at public pools, is that if there's problem, if there's something reported, then an inspector will go in to analyse why that problem is occurring", he said.

While most bacteria are destroyed through filtration and chemicals such as chlorine, there is one that chlorine cannot kill - the single-celled parasite Cryptosporidium.

The parasite is excreted in the faeces of humans and animals and most commonly enters pool water from a leaky nappy or child's mishap, or from the skin of people who don't wash before they swim .

When swallowed, Cryptosporidium can cause a serious illness, which is characterised by severe stomach cramps.

As there is currently no cure for the illness, Cryptosporidiosis, the consequences for some people can be fatal.

Prof Gazzard: Infections can be fatal

Professor Gazzard, a Gastroenterologist and specialist in HIV Medicine at London's Chelsea and Westminster Hospital says: "People who have a normal immune system get quite brisk diarrhoea a few days later, which last for about four to five days and they get over it and get better.

"The problem really is that if you're immuno-compromised - for example if you've got Aids, or you've had drugs to compromise your immune system then you get a much more devastating illness where you can get very, very major diarrhoea that can go on for days or months and indeed can kill you sometimes."

Although outbreaks of "Crypto" from swimming pool water are rare in the UK, there have been reported cases. But it is far more common abroad where hygiene standards vary, as at least 60 Britons found out while holidaying at a resort in Majorca this month.

Swimmers are being asked to practise better hygiene

By better educating people about the risks of infection, national sports and recreation groups hope to change people's long held habits.

They say by taking a shower before swimming we can significantly reduce the number of germs on our bodies, so the cleaner our bodies - so the cleaner the pool water.

And it was that logic which has led some European countries such as Germany and Austria to make a pre-swim shower standard practice and why certain groups here, want Britain to follow suit.