Stories about hospital superbugs abound and even the most hardy of us would think twice about eating chicken that had been kept warm on a grill or biting into an unrefrigerated tuna sandwich. But over the next few weeks, thousands of us will be diving into swimming pools that could easily contain a variety of bugs and germs including faecal bacteria, cryptosporidium and E coli.

"When people are ill during or after a holiday they usually assume it's because of something they've eaten but it could easily be caused by the water they've been swimming in, " says Frank Brehany of consumer rights group HolidayTravelWatch. He has had reports of Nile cruise ships using river water in their swimming pools and water features.

A recent investigation by scientists for Which? magazine of 80 swimming pools tested in Corfu and Majorca found that a quarter of those tested were a health hazard. A further 29 offered potential risks to the health of those using them and six were heavily contaminated with faecal bacteria. Remarkably, only two pools were free of pollutants and were properly disinfected, according to Which? .

"What you should be seeing is crystal-clear, blue water. If you're not seeing that, that's an immediate warning sign, " says Kilian Fisher, CEO of the Institute of Leisure and Amenity Management, Ireland (ILAM). "Now, even if you see crystal-clear nice blue water, that doesn't necessarily mean it's totally safe. What you should do is go and ask the pool or hotel manager if the water in the pool is tested. Even ask to see the water test records, if there is concern."

Doctors calculate that there can be up to 30 different bugs in a swimming pool. Cryptosporidium and E coli, both of which can cause diarrhoea and vomiting, have only one cause in water . . . faecal matter. In parts of the world where cholera and polio still exist, these two could technically exist in dirty pool water, although this is relatively unlikely. Some pools may also harbour low levels of a bacterium called pseudomonas aeruginosa, responsible for skin and ear infections.

There have also been reports of giardia, a parasite that causes chronic diarrhoea, being transmitted at a waterslide park. Pseudomonas, another water-borne bacterium, can cause inflammation of the skin, although it is usually transmitted in jacuzzis rather than swimming pools. In most of these cases, the infection is usually easily treatable but can still ruin a holiday.

Among the unwelcome substances found in badly managed pools are sweat, urine, mucus, saliva, dead skin and faecal matter, as well as sun cream and traces of cosmetics. The presence of these unwelcome additions should have been minimised by the use of proper disinfectants and pool filtration. Though there are no Europe-wide industry standards, in Ireland you can check if a pool is safe by seeing if it has been awarded a White Flag. Like the Blue Flag awards for beaches, this new initiative by the ILAM awards White Flags to pools and fitness centres that are hygienic, safe and well managed. "We are working with a European organisation, EHFA [European Health and Fitness Association] to have standards for Europe. So while the White Flag will only be in Ireland, there will be equivalent European standards, " says Fisher.

Until those standards are set, there are several ways you can check a pool's safety to keep healthy on holiday. For example, outdoor pools are best . . . ultraviolet light from the sun kills a lot of the bugs that could be lurking in the water. If you can see sand or dirt in the bottom of a pool, chances are the filtration system isn't working properly. "All pools should have continuous circulation, which brings the water through filtration pumps and disinfectant. That should be constant while the pool is in use, " says Fisher. "How you test that is to see where the outlets in the pool wall are letting water into the pool. Put your hand down and if you can't feel anything coming out, the circulation is not on. You should feel the pressure of the water coming into the pool."

Drains or skimming systems in the pool are another thing to look out for . . . if you can see flies or other debris floating on the top of the pool, they are probably not working. The best kinds of drains to look out for are deck-level channels running around the pool. As the water overflows, these drains filter out dirt and other debris.

If you have any doubts about the safety of the water in a pool, ask to see water test records. "If they don't have them available, I'd get very suspicious, " says Fisher. "That should alert anybody who has some concerns, if the management are refusing or if they seem blank or haven't got a clue. I'd start getting very concerned then." So look for crystal-clear water, sunshine, a good filtration system and deck-level drains . . . and enjoy a relaxing, safe and healthy holiday.

Additional reporting by Niamh O'Doherty

HOW TO STAY SAFE
>> Always shower before entering the water
>> Ensure babies and toddlers wear waterproof nappies
>> Bigger pools have a greater risk of contamination . . .wherever possible, opt for hotels with smaller pools
>> If a pool is cloudy or smells strongly of chlorine or any other chemical it could be a sign of contamination.
>> After swimming, wash with soap and apply a good moisturiser
The bugs in your pool
>> Cryptosporidium: A microscopic parasite that causes diarrhoea lasting up to two weeks. It's only serious to people with immune deficiency.
>>Pseudomonas aeruginosa: Can affect the lungs, urinary tract and open wounds and cause vomiting and diarrhoea.
>>Acanthamoeba: Can enter the body by cuts on the skin or the surface of the eye, causing swelling and pain in the eyeball >>Ecoli: A form of bacteria that lives in the intestines and helps digest food. If certain forms of Ecoli get into other parts of the body they can cause severe stomach upset. Children are worst affected and in certain cases it can lead to kidney damage or even death.