A study by virologists at Imperial College London, which is awaiting peer-review, suggests the risk of COVID-19 transmission in swimming pool water is "incredibly low".

The study looked at the effects of swimming pool water on SARS-CoV-2, the virus which causes COVID-19, to assess the amount of time and contact needed to inactivate the virus in varying chlorine and pH levels.

The research established that 1.5mg per litre of free chlorine, coupled with a pH between 7-7.2 reduced the infectivity of the virus more than 1,000-fold within 30 seconds.

Additional testing of different free chlorine and pH ranges confirmed that chlorine in swimming pool water was more effective with a lower pH. This is in line with current guidance for swimming pool operation.

The research – which was commissioned by Swim England and Water Babies, and supported by RLSS UK – was undertaken by virologist and expert in respiratory viruses, Professor Wendy Barclay, together with research associate Dr Jonathan Brown and research technician Maya Moshe.

Professor Barclay said: “We performed these experiments at our high containment laboratories in London.

"Under these safe conditions, we are able to measure the ability of the virus to infect cells, which is the first step in its transmission.

"By mixing the virus with swimming pool water, we could show that the virus does not survive, meaning the water was no longer infectious.

"That, coupled with the huge dilution factor of virus that might find its way into a swimming pool from an infected person, suggests the chance of contracting COVID-19 from swimming pool water is negligible."