Swimming pools – infection control

Swimming pools can be contaminated with Cryptosporidium, a parasite that causes gastroenteritis in humans. Cryptosporidium is highly contagious and can be passed from infected humans, cattle or other domestic animals. Outbreaks have been associated with swimming pools where infected swimmers contaminate the pool with the parasite from their faeces. With adequate hygiene and healthy swimming behaviour, pool contamination can be prevented.


The gastrointestinal illness cryptosporidiosis is caused by the parasite Cryptosporidium parvum.Possible sources of contamination include domestic animals such as pets, and farm animals such as cattle. The parasite is transmitted by the faecal oral route, by eating or drinking contaminated foods or water. The parasite lives in the bowel and is found in the faeces of infected humans. Outbreaks of cryptosporidiosis can occur when swimmers accidentally swallow pool water contaminated by the parasite.

Cryptosporidiosis is very contagious

One infected person can pass enough parasites in a single visit to contaminate a large swimming pool. The parasites are highly resistant to chlorine, the usual form of pool disinfection. Swallowing as few as two parasites can lead to infection.

Symptoms of cryptosporidiosis

The symptoms of cryptosporidiosis are usually mild, but illness can be more severe for people with impaired immunity, in children and pregnant women. After infection, it can take one to twelve days (on average seven days) before you become ill.

Symptoms may include:

  • Profuse, watery diarrhoea, often with abdominal cramping
  • Bloating
  • Fever
  • Loss of appetite, fatigue, nausea and vomiting.

The symptoms usually last for about two weeks. People with impaired immunity may be ill for longer. An infected person can continue to shed the parasite in their faeces for at least two weeks after recovery. 

Treatment for cryptosporidiosis

There is no specific treatment for cryptosporidiosis. Consult your doctor for medical advice.

Preventing Cryptosporidium contamination of swimming pool water

Poor hygiene practices mean that most swimmers retain some faeces on their body. This can be rinsed into the pool while swimming.

To help prevent such contamination events you should:

  • Never swim in a pool if you have diarrhoea or if you have had diarrhoea in the past two weeks
  • Shower and wash thoroughly with soap before entering the pool
  • Wash your hands with soap after going to the toilet or changing a nappy
  • Avoid swallowing pool water
  • Never change nappies by the pool side.


Preventing pool contamination by babies and toddlers

Faecal accidents by infected swimmers such as infants and toddlers (particularly those who are not toilet trained) are a high risk of contamination for the pool.

To prevent faecal contamination of pool water you should:

  • Never change your child’s nappy by the pool side – use the bathroom or nappy-change facilities
  • Use ‘aqua nappies’ for infants to better contain faeces
  • Dress toddlers in close-fitting swimsuits to better contain faeces
  • Change nappies regularly and take children for frequent trips to the toilet, to reduce the risk of accidents
  • Occasionally check your child’s nappy and bathers for faecal discharge
  • Wash your hands with soap after going to the toilet and after changing nappies
  • Never rinse your hands in the pool water after a trip to the toilet or after changing your child’s nappy
  • Report any faecal accidents to swimming pool staff.

If you or your family develop a gastrointestinal illness after swimming at a public pool, contact the pool manager so that any illness trends can be monitored.

Where to get help

  • Department of Health Water Program Tel. 1300 761 874
  • Your doctor
  • Your local council


Things to remember

  • Cryptosporidiosis is a highly contagious infection.
  • Do not use a swimming pool if you have had diarrhoea in the previous two weeks.
  • Always practise good hygiene before swimming and after going to the toilet.
  • Tell the pool manager if you become sick after swimming at a public pool.



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