Please note: While some information will still be current in a year, other information may already be out of date in three months time. If you are in any doubt, please feel free to ask.


My son (aged 7) is due to start swimming with school in January. The pool used by the school is not chlorinated but the water is cleaned by ultra-violet light.

Would this pose any infection risk for someone with CF?

Thank you.
Dear questioner,
we already had a lot of questions on the topic of usage of public swimming pools, jacuzzis and spa bath. Please find first of all a detailed answer on this topic in general under the following link:[showitem]=2873&tx_expertadvice_pi1[search]=jacuzzis

From this answer it becomes clear, that in general well chlorinated pools are not a problem for CF patients, however, as you can see in the mentioned studies in the answer, that the detection rate of Pseudomonas aerugionsa in chlorinated public pools varies from country to country and maybe even from public pool to public pool.
Your question is about the water disinfection with UV light. A literature research revealed that water disinfection with UV light is an effective method, in here it is important to use the right wavelength of the UV light and to follow exactly the manufacturers guidelines and have a good maintenance of the device. For private pools I found the statement, that with UV disinfection 80% of the normal amount of chlorine necessary for water disinfection could be saved—therefore I assume, that a certain amount of chlorination will probably still be needed. For public pools, there are different regulations in each country. In Germany, for example, a certain chlorine concentration in the water of public pools is mandatory and UV-disinfection is at the moment not an alternative allowed in the legal regulationa, however teams are working on an update to integrate this method in the future. Independently from the regulations and methods used in the UK, the most important thing is the measurable effectiveness of a certain water disinfection method. This means, there are certain quality criteria, the water has to fulfill, e.g. in Germany E. coli and Pseudomonas aeruginosa should not be detectable in 100ml of pool water, Legionella should even not be detectable in 1ml of pool water. All other germs are measured as “colony forming units”, the number of 100 colony forming untis/ml pool water should not be exceeded. So it would be the safest way to talk to owner of the pool and have a look at the test results of his water quality—are they within the legal regulations? In case of doubt, a water sample could be tested.
Hope this helps,
Best regards,
Dr. Daniela d’Alquen (Coordinator of the Central English Archive of ECORN-CF)
The answer is edited by: Prof Judy Bradley