Health and Safety

Cryptosporidium and Swimming Pools

Pembrokeshire County Council together with all local authorities in Wales are participating in a project to review the provisions in place to manage Cryptosporidium in Swimming Pools.

Cryptosporidium is a germ that causes diarrhoea. Crypto, short for Cryptosporidium is found in infected people's stools and cannot be seen by the naked eye. The germ is protected by an outer shell that allows it to survive for long periods of time and makes it resistant to chlorine disinfection found in pools.

In recent years, Crypto has become recognized as one of the most common causes of waterborne illness. There have been a number of Crypto outbreaks reported in Wales. A pool in Merthyr Tydfil was closed for 6 months due to an outbreak, with victims being detected from a considerable catchment area.

Swimming is a terrific exercise but the responsibility of keeping it healthy is shared between bathers and pool operators.

EHOs will also be visiting every pool in the County. The visits will focus on building an understanding of the public health issues associated with Cryptosporidium and the implementation of practical measures to minimise the introduction and transmission of Cryptosporidium, specifically:

  • Reporting and recording of action taken following faecal contamination: in pool water, changing rooms and toilet facilities 
  • Staff training and training records on the management of faecal contamination 
  • Advice to customers regarding use of the pool when suffering with diarrhoea and/or vomiting 
  • Advice to customers regarding children who are not toilet trained 
  • Pool water treatment records - failures and action taken, particularly in relation to filtration and backwash.

Here are six "P-L-E-A-S" for pool users that promote healthy swimming:

  • Please don't swim when you have diarrhoea or have had diarrhoea within the past 48hrs
  • Please don't swim for 14 days after been diagnosed with Cryptosporidiosis
  • Please take a shower before swimming and wash your hands after using the toilet or changing nappies
  • Please ensure that babies and children wear purpose made swimming nappies. Please take your child on bathroom breaks
  • Please don't swallow water

As part of the project a video has been produced to provide further guidance to both pool operators and users regarding Cryptosporidium and Swimming Pools. This can be viewed on youtube:

Further guidance can also be found in the PWTAG Code of Practice: The management and treatment of swimming pool water (January 2013). The COP can be downloaded from The Pool Water Treatment Advisory Group


Contact details:
For further information on Cryptosporidium or the project being undertaken, please contact the health and safey duty officer on:

Tel: 01437 775631
Email: health&


ID: 1541, revised 17/03/2023